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The significance of diseases and parasites of the muskrat (Ondatrazibethica) in British Columbia Musfeldt, Lola Wyndmere 1947

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THE SIGNIFICANCE. OF DISEASES.AMD PARASITES OF. THE MUSKRAT?'(ONDATRA ZIBETHICA) •by: Iola W. Musfeldt A.Thesis submitted i n P a r t i a l Fulfilment of the Requirements f o r the Degree of Master of Arts i n the Department of Zoology The-University of B r i t i s h Columbia, October,. 1947. ACKNOWLEDGamrS For the completion of this investigation, the author wishes to acknowledge kindnesses on the part of many Game Commission and University associates. These include Commissioner F.R. Butler and members of the Pr o v i n c i a l Game Commission and of the University of B.C.; Dr. C E . P h i l l i p s , Department of Animal Husbandry and Dr. J.R. Adams, Department of Zoology. My sincere appreciation i s tendered to Dr. W.A. Clemens and Dr. I.MeT. Cowan for recommendation f o r f i n a n c i a l grants, without which completion of t h i s study may have been impossible, also f o r use of laboratory space and equipment. To Dr. Cowan I am also g r a t e f u l for directing my survey throughout i t s l i m i t s . TABLE CE CONTENTS Chapter ^age In.tr o.duction... r.-- - — - , — . — 1 H i s t o r i c a l Review -2 Methods of Study l l The Muskrat i n B r i t i s h Columbia 15 Diseases and Parasites of the Muskrat 38 Diseases and Pathologies 39 Parasites - — 53 Results, of t h i s Investigation 84 Significance of Disease and Parasitism i n B r i t i s h Columbia Muskrats 86 Conclusions . 89 I l l u s t r a t i o n s • 92 References 100 Abstract 107 I 1 LTHE SIGNIFICANCE OP DISEASES AND PARASITES ••OF THE MUSKRAT (ONDATRA ZIBETHICA) IN BRITISH COLUMBIA. INTRODUCTION In the f a l l of 1944, as a preliminary to the present study, the investigator undertook a survey of the parasites of the muskrat at Burnaby Lake (Vancouver, B.C.). The r e s u l t s of t h i s survey indicated that t h i s problem was worthy of con-tinuation throughout the province of B r i t i s h Columbia, In order to complete such an investigation, a knowledge of the d i s t r i b u t i o n of t h i s p r o l i f i c fur-bearer and a means to obtain many muskrat carcasses were necessary. As a r e s u l t of returns from an 'outline questionnaire 1 sent to registered trappers, considerable information regarding the muskrat was obtained. Prom October 15, 1944 to May 15, 1947, 202 skinned carcasses were co l l e c t e d on which parasite and disease examin-ations were performed. The purpose of thi s thesis i s to present an analysis of the information on the problem oftdiseases and parasites of the muskrat i n i t s existing state i n t h i s province. Previous studies i n t h i s f i e l d are also summarized. 2 HISTORICAL' REVIEW The muskrat, one of the staple fur-bearers of North America, has been studied extensively i n the eastern and southern parts of t h i s continent. However, "there are few important i n q u i r i e s regarding t h i s p r o l i f i c animal i n i t s western ranges. Several investigations have taken place i n Europe, since i t s introduction from America. Since the early years of w i l d l i f e study, a great bulk of l i t e r a t u r e has accumulated on the l i f e h i s t o r y , d i s t r i b u t i o n , diseases and parasites of the muskrat. Among the e a r l i e r publications are those of R. MacEarlane (1905) and E.T. Seton (1909), i n which several pages are devoted to the muskrat i n the Mackenzie River d i s t r i c t . There i s a l s o the revisionary work of Ned H o l l i s t e r (1911) on the d i s t r i -bution of the muskrat i n North America. The few major studies on the muskrat west of the Rocky Mountains have been i n C a l i f o r n i a where T.I. Storer (1933), CA. Sooter (1946) and A.L. Hensley and H. Twining (1946) have completed l i f e h i s t o r y and d i s t r i b u t i o n surveys. While b i r d and mammal surveys carried out i n various l o c a l i t i e s i n B r i t i s h Columbia by H.S. Swarth (1924), I. MoT. Cowan (1939) and J.A. Munro (1947) include muskrat. The diseases and e s p e c i a l l y the.parasites of the muskrat have been studied quite extensively. However, i t i s apparent from the available l i t e r a t u r e that no 3 o parasite-logical study has been undertaken i n the western part of the species range. According to the l i t e r a t u r e , publications on the diseases are l i m i t e d ^to the ...papers of T. Warwick (1934) i n England, F.R. Smith (1938) and H.L. Dozier (1943) i n Mary-land; an unpublished report from P.L. Errington (1943) i n Iowa and a few scattered references i n the papers of ' MacFarlane (1909), W.M. Rush (1927), R.L. Rausch (1946), J i E . S h i l l i n g e r (1933), J.H. Brown (1944) and others. A. E. Vfoodhead (1930) reviews c o c c i d i o s i s i n the farmed muskrat. Early l i t e r a t u r e on parasites includes a report by Linton i n 1884, who noted that the muskrat was host to l a r v a l cestodes. - In 1888, Leidy mentions f i n d i n g two species of trematodes i n the small i n t e s t i n e which he i d e n t i f i e d as Echinostomum echinatum Zedar and Amphistomum  subtriquetrum Reed. The l a t t e r species was l a t e r renamed by F.D. Barker as Wardius zibethicus. Apparently undated, i s the report of un i d e n t i f i e d f i l a r i a from the muskrat by B. H. Ransom at the Bureau of Animal Industry, Washington, D.C. Another early report was S t i l e s and Hassel i n 1894, who i d e n t i f i e d l a r v a l cestodes from the muskrat i n Pennsylvania. C j ^ c e V t h ^ a great amount of data has been c o l l e c t e d on the parasites of 4 the muskrat i n many parts of North America and Europe. Table 1 presents a summary of the reported para-s i t e s , 'their s i t e of i n f e c t i o n , location of report and the investigator. I t i s possible that t h i s summary has a few omissions. I t may be noted from t h i s table that although the species of muskrat varies i n range throughout North •America, the d i f f e r e n t species of parasites have remained constant. This i s also evident i n England where the muskrat has been introduced. There, it"has introduced i t s parasites and has as yet acquired no new normal ones. I t i s noted too, that some of these parasites have an extensive d i s t r i b u t i o n . These include Quinqueserialis  quinqueserialis, C a p i l l a r i a ransomia, Hymenolepis evaginata and Cysticercus f a s c i o l a r i s which occur throughout North America as well as i n Great B r i t a i n . It i s i n t e r e s t i n g to observe also the geographical d i s t r i b u t i o n of the reported parasites in.North America. The species of trematodes tend to be more numerous i n the northern areas, while species of nematodes are more numerous i n the southern ranges. Besides i t s normal parasites, the muskrat has been found infected with c e r t a i n accidental parasites both i n England and North America. Of the former, Fa s c i o l a henatica i s the only accidental i n f e c t i o n while i n the l a t t e r , Schizotaenia sp., normally a porcupine parasite, has been reported. ENDOPARASITES ECTOPARASITES Small Intestine External Body Trematodes Mites Acarina h3 H P 4 o 3* H-m •d o H* I. CD S H f f f l ) CO c+OH-CQ O* p £ T O c+4 4 H" C O p ops o s p-p 3? o p 3 SB P" P & O CQ 3 3 co •d CO e t o P P« P O 3* h" 3 O ca c t O I 3 P oq co 4 3 SOWS p 3 P CO 4 ctCQ Xf << p ct4 H4 cop P F"4 CQ o O! & w 3 O CD c t o 3 C 3 o o p H h* c t M 0 2 P 3* <o co t-»cy c t O 4 CO p 3 & p o s p P" p o S3* H" 3 O CO c t o 3 C 3 CO <* o H c t 3 cn P 4 o o •g-S3> Oq P CO •d O 3 c t P 4 H -O H CO H 3 H* 3 3 CD o ^  CQ O 3 P P< P F o CQ h* P 3 P tr* H -CQ c t 4 O •d 4 CQ CQ f 4 « < ! H P 3 P" H O 31 P O 3 <<* m CD CQ CD • d H" 3 h* oq co 4 t-3 CO c t 4 P oq o 3 << CO CQ CO CQ •d 3 H-oq CD 4 P-o p &t CD H H-P P 3 3 P> P • • • • • £)•••• 3P Hp R°co0 H4 COCO CO r^* > H-0 3 CO co roo\4^J\ « ; CQ P. CO « . « • » C R°H4 H>3CD o Vjj3U) -V A 3 4=1-* —co—<n p . .w ro • » • p • • 3 > td H " co > 3 P CO 4 co - ^ B VJL* -CD ' V/v p , — ro C-l • p • CQ • o tu 3*P - C O £ 4 > H H CO 3 P CO 4 Jxf *r3 "TJ • « • tr* o o p • • ^ oo cd CO CD 8» P ^ <5 J > CO • 4 CO - ^ . ^ 3 3 co ~o V . 0 ro • • • O O O O CD cx) rxttdf* CO CD CO CO p p P H* CD CD CD 4 4 4 ^ H - - - 0 0 V . 0 KJ)KJ> 0 0 ^ J ^ - o c o Q CO o CO 3 3 C-l 4 .tr ro pa co 3 0 0 ^ 1 9 CO 3 H* c t cr U3 0 0 LOCATION IN HOST GLASS PARASITE . AREA RECORDED CITATION Echlnochasmus s c h w a r t z l i South.east Texas New Orleans O n t a r i o , Canada Asa C.Chandler (»4l) Elm.E.Boyd & Rpbt.J. Reiber («42) R.Law &.A.Kennedy ('32) P h a g i c o l a nana New Orleans Elm.E.Boyd & Robt.J. Reiber («4<2) sstine CO CD •d n Nudacotyle n o v i c i a South.east Texas L o u i s i a n a Michigan O n t a r i o , Canada Asa C. Chandler («4l) Geo.H. Perm J r . ( '42) D.J.Amell («42) R. Law & A. Kenn edy (' 32) •p c H Echlnoparyphlum oontlguum Nebraska O n t a r i o , Canada P.D.Barker ('15) R.Law & A.Kennedy (832) 00 w H H fH f H P h a g i c o l a l a n g i n i f o r m i s ' South.east Texas Asa C.Chandler («4l) EH M CQ A l a f i a mustelae Eastern Canada Ontario J . A . A l l e n ('34) R.Law & A.Kennedy ('32) O Allassogonoporous margin-a l i a : Michigan O l i v i e r («38) Urotrema s h i l l i n g e r l Maryland P r i c e ( '3D L.R.Penner ('41) Pseudodiscus z i b e t h i c u s Michigan D.J.Ameel ( «42) (1) Small Intestine Cestodes Hymenolepis- evaglnata Nebraska -L o u i s i a n a East.Canada C t . B r i t a i n Michigan Ontario ; A l b e r t a Ohio F.D.Barker ('15) Geo.H.Penn Jr.('42) J . A . A l l e n (»34) H.A.Bayliss 1%35) D.J.Ameel I'42) R.Law & A.Kennedy ('32) W.E.Swales (»33) R.L.Rausch («46) ENDO-PARASITES - ENDOPARASITES Small i n t e s t H M a o o ine and cecu n Small Intestine Small Intest-ine ATION; HOST Protozoa Nematodes C e i t ^ -bdes : CLASS CLASS Trichomonas Eimerla steidae Q-lardla ondatrae Strongyloldes ratti (var.ondatrae) Longlstriata adunca Retioularia ondatrae Longlstriata dalrymplll Trichostrongylus flberlus Capillaria ransomia Trlchurls, opaca Nematospinoldes longl- ] splculatus : i Taenia crassicallis Anomotaenla telescoplca , PARASITE • f o H " CO - H * P Eastern Car Louisiana South, east Louisiana South.east South.east Eastern Car Nebraska Eastern Car Michigan Ohio Eastern Car Michigan Ohio Washington, New Jersey Maryland Nebraska AREA lada Texas Texas Texas P p> P lada lada , D.C. RECORDED CD o • • CD 3 3 •£ r o • > • > H H CD 3 cpw CD CD O 4 • 3 CD S < £3 « - 1-3 4 c , p 4 <J • H " -—CO r o -— < j j > CQ P o • o B" 8. i - 1 CD 4 H CD o » • ' >TC) CD 3 3 4 • : r o Asa C.Chandler (»4l) > CQ P o o p> H CD 4 CH e > e fc H CD 3 H o o * e L - « C H > 0 9 0 • • P 3 H P £ CD H 4 CO CD CD P? a H 3 CD 3 ^ _ ^ 4 - C ^ r o - P H O V - r - * J \ mot, • 9 • • • • p 3 H CCD H CO CD CD O H 3 4 • P • H* !*r 3 o 3 CO s • is • CO 3 H BP vjj 00 F.D.Barker (»15) CITATION LOCATION IN HOST CLASS PARASITE AREA RECORDED CITATION ; ; x\ l o tfematoda Nematoda Physolaptera sp* . Louisiana Eastern United States Geo.H.Penn Jr.(«^2) G e c S h i l l l n g e r (»33) ai ' B Protozoa Coccidia Eastern u n i t e d States Geo.Shillinger («33) o 03 Sestoda Schlzotaenla v a r i a b i l i s & S.Americana Minnesota Olsen ('39) Quinqueserialis quinque-s e r i a l i s (Notocotylus quinqueserialls) (2) Nebraska Eastern Canada Gt. B r i t a i n Michigan Washington Ohio Ontario Michigan & Pennsylvania F.D.Barker ( '15) J.A.Allen (>3*0 H.A.Baylisa I'35) D. J.Ameel ('42J H.E.Metcalf ( "15 coll.) R.L.Rausch («46) R.Law & A.Kennedy ("32) E. C.Herber ('^2) CO w FH ine and cac odes C atatropis filamentls (3) Nebraska Eastern Canada HS&ffftgn F.D.Barker («15) ARASI1 ine and cac remati Hemistomum craterum Nebraska? Eastern Canada Ontario F.D.Barker (»15) J.A.Allen («34) R.Law & A.Kennedy («32) ENDOP +> . CD •P : & .. H EH Wardlus zibethlcus (4) : .Nebraska Eastern Canada Gt.Bri t a i n Ohio Ontario F.D.Barker ("15) J.A.Allen Ojk) Tom Warwick ( ,36) R.L.Rausch ( %kb) R.Law & A.Kennedy (»32) • • Notocotyltia urbanensis , Maryland Wm.Cort ('I/O A.HassalL Tlo92)col.) • Cntestine k cecum Nematode Trichostrongylus f l b e r l u s Nebraska F.D.Barker ("15) Colon Trema-todes Paramo no s t omum 0 . ^ 5 ) Louisiana Southeast .Texas Geo.H.Penn Jr.«ty2) v Asa C.Chandler («4l) E.W.Price (»3l) Paramonostomum echlnum Colorado Harrah ( '22)(Gable "16 cc LOCATION IN HOST CLASS PARASITE AREA RECORDED CITATION OQ Schistosomatium d o u t h i t t i Minnesota Michigan D.J.Ameel (5^2), L.R.Penner ('38) u CD i> <0 T3 o OpJ^stor^cMs^t o nkae Minne so ta Michigan L.R.Penner ( » 3 9 ) F.G.Wallace ( « 3 9 ) •H •J CI} s © Psllostomum ondatrae Eastern Canada Ontario J.A.Allen (°3*0 R.Law & A.Kennedy ( ' 3 2 ) u EH F a s c i o l a hepatica G t . B r i t a i n Tom Warwick ('36) >' todes C a p i l l a r l a hepatica G t . B r i t a i n Eastern Canada Michigan H.A.Bayllsa ('35) J.A.Allen ( ' 3 ^ ) D.J.Ameel (»#2) •H as s Q) •=» Hepatlcola hepatica G t . B r i t a i n Ontario Tom Warwick (l3k) R.Law & A.Kennedy (32) ENDOPARASITEi CD 00 CD -d Cysticercus f a s c l o l a r i s (larvae of Taenia taenia-formis (Batsch) 1786) G t . B r i t a i n Washington Penn. Maryland Eastern Canada Philadelphia Ontario Michigan Ohio H.A.Baylias ( « 3 5 ) Linton (1884-) F.R.Smith ( (38) J.A.Allen { » 3 > ) - ('8$ & «05) R.Law & A.Kennedy (»32) R.E.Kuntz (»42>) R.L.Rausch («^6) ENDOPARASITEi <H Cesto Taenia, t e n u c o l l i s larvae (Cysticercus innomlnabus hypudaei Leuk 1857) (6) G t . B r i t a i n Ontario, Canada H.A.Baylis ( « 3 5 ) M.S.Skinner ( « 3 5 ) Urocystldium gemmiparum Germany (?) Biddard ('140 Cladotaenia sp. Michigan D.J.Ameel ( 842) L.R.Penner (838) G a l l duct ft bladder Trema-tode Monostomum a f f i n e Pennsylvania J.Leldy (1858) L_ Omentum Destode Cysticercus f a s c l o l a r i s Washington, Penn. Michigan Linton (188*4-) D.J.Ameel («42) LOCATION IN HOST CLASS PARASITE AREA RECORDED CITATION Spleen Trema-tode Schistosomatium d o u t h l t t i Michigan Minnesota D. J . Ameel («42) L. R. Penner ( '38) 03 Blood TRema-tode ; Schlstosomatium d o u t h l t t i Minnesota and Michigan L.R.Penner"('38) PARASITE Blood F l l a r l a D l r o f l l a r i a sp. Maryland F.R.Smith ('38) PARASITE Litomosoldes c a r i n i i . ( m i c r o f i l a r i a adults) South.east Teaas Asa C.Chandler ( '41.) ENDO Arach-nida Arachnida -Porocephalus c r o t a l l (nymphs) Louisiana Geo.H.Penn Jr.(«42) Lung Trema-tode • Paragonimus sp.(7) ' Gt . B r i t a i n ] Minnesota Tom Warwick ( 136) DiJ.Amael ('32) -TABLE I - Parasite Records for the Muskrat (Ondatra sp.) as reported i n the l i t e r a t u r e to 1946. Footnotes: (1) = U.lasiurensis A l l c a t a ('32) U.minuta Macy '33 (2) Notocotyle qulnqueserlale Barker and Laughlin = Quinqueserialis Hindiu = Naviformla » Kossackia Barkeria = quinqueserialis (3) C f i l a m e n t i a , Price = C. fllambriata, Barker (4) Wardius zibethicus, Barker = Amphlstomum subtriquetrum, Liedy ('84)= Cladorchls subtriquetrus Warwick (1936) (5) = Neoparamonostommm (6) Cysticercus innomlnabue hypudaei Leuk 1857 - Cysticercus talpae Rudolphl 1819 H : (7) - not t y p i c a l rodent parasites Not l i s t e d : W.Henry Leigh ('40) - reported protozoan and helminth parasites i n I l l i n o i s • .. 11 METHODS of STUDY It was impossible to investigate personally the many areas i n the province of B r i t i s h Columbia that the muskrat inhabits. In order to overcome t h i s s i t u a t i o n , a pamphlet consisting of a questionnaire with a l e t t e r of introduction to t h i s problem was sent to 750 registered trappers. The trappers contacted were chosen from the " L i s t of Names and Addresses" of Holders of Special and Extra-special (trappers) Firearms licenses issued under the B.C. Game Act" which is.,compiled by the B.C. P r o v i n c i a l Game Commission. Similar pamphlets were sent also to the game-wardens throughout the province. The returned questionnaires were segregated as "positive returns" i f the l i s t of fur-bearers trapped included muskrat, and as "negative returns" i f no muskrat were taken. Each of these groups was divided into the area i n which the tr,apline was located. (Plate I. , Map of B r i t i s h Columbia). From the returns of thi s questionaire considerable information was obtained regarding the d i s t r i b u t i o n of the muskrat; areas i n which i t i s trapped; other fur-bearers trapped i n the same area; number of muskrat c o l l e c t e d and diseases a f f e c t i n g i t . Also through this pamphlet, both trappers and game-wardens were requested to send to the University "expres's c o l l e c t " fresh skinned muskrat carcasses during 12 trapping season f o r disease and parasite examination. In cases where the carcasses could not he received within a couple of days, there was sent to the trapper or game-warden a quart of 100$ Formalin with directions f o r i t s in use. These directions were to add the formaldehyde to a p a i l of water and place the carcasses i n t h i s solution for 24 hours. Following t h i s procedure they could be safely forwarded to the u n i v e r s i t y . When a carcass was received i t was numbered according to t r a p l i n e l o c a t i o n and the following routine• examination for diseases and parasites was performed. Several observations, i n c i d e n t a l to the actual examination, were recorded. These included weight, sex, measurements, sexual a c t i v i t y and scars. Also recorded and preserved were diseased areas and i n several instances, complete sk u l l s and male g e n i t a l organs (testes and seminal v e s i c l e s ) . A complete examination of the i n t e r n a l organs included noting the condition of the respiratory, urinogenital, c i r c u l a t o r y and digestive systems as well as the general condition of the body. The digestive t r a c t was removed from the animal, tagged with the i d e n t i f i c a t i o n number and preserved i n 5$ formalin. This preserved the i n t e s t i n a l tract and removed decomposition odours. Just, pr i o r to p a r a s i t i c examination i t was soaked i n water f o r a few hours to remove the formalin. 13 For the study of the i n t e r n a l parasites, the entire digestive tract was divided into the regions of stomach, upper small i n t e s t i n e , lower small i n t e s t i n e , cecum and colon. The small i n t e s t i n e was divided i n ha l f , that-portion following the stomach was designated: as "upper small i n t e s t i n e " while the "lower small i n t e s t i n e " was that attached to the cecum. The "cecum" included the cjscum proper as well as that portion of the colon which i s the same diameter as the cecum. The "colon" was the remainder of the colon and rectum. Each segment was s l i t and the contents were washed into a millimeter-mesh sieve* The piece of i n t e s t i n a l tract was run over the l e f t index finger and cleaned.with water running through a glass t i p on the water fawcett hose to remove adhering parasites. The sieve contents were washed with water to remove f i l t e r a b l e debris. The remaining material was washed into a glass bowl. The parasites thus showed up whitish and opaque when examined against a black background. In this manner, any parasites greater than one millimeter were counted and co l l e c t e d for i d e n t i f i c a t i o n . Protozoan parasites were not accounted because usually 24 hours had lapsed before receipt of the carcass. Hence, erroneous identification would res u l t regarding specimens that might have been found. 14 For s p e c i f i c i d e n t i f i c a t i o n , i n a high i n f e c t i o n , a representative number of individuals of each species was co l l e c t e d . Otherwise, a l l the parasites were recovered and preserved i n formol-alcohol.. The trematodes were stained i n a modified Mallory T r i p l e Stain 7 7; the cestodes, i n Borax-Carmine or Acetic Alum Carmine, while the nematodes were mounted unstained i n pure g l y c e r o l . The acantho-cephalan parasite was mounted either unstained or stained i n Acetic Alum Carmine. # The technique used i n t h i s work was devised by the author. It consisted of using 1:10 water d i l u t i o n s of the regular Mallory Stains #1 and #2. I f a specimen was overstained i n Mallory #1, either acid or basic 75% alcohol was used to destain. S i m i l a r l y , excess Mallory #2 s t a i n was removed by basic. 75% alcohol. Phenol-xylol was used f o r dehydration and balsam mounts. The paler stained specimens howed the best d i f f e r e n t i a t i o n . I t was found that t h i s s t a i n i s most successful f o r the small trematodes only. 15 THE MUSKRAT IN BRITISH COLUMBIA It w i l l be noted from Plate I that i n B r i t i s h , Columbia there are two subspecies of muskrat, Ondatra  zibethica osoyoosensis and 0. z. spatulata. The former i s of more southern d i s t r i b u t i o n while the l a t t e r occupies the, northern range. The coastal intergradation of the two subspecies apparently occurs i n the Skeena d i s t r i c t . The d i s t r i b u t i o n shown i n t h i s map i s only general, as sub-sequent discussion w i l l reveal that much of the t e r r a i n of t h i s province i s unsuitable f o r muskrat inhabitation. Por the purpose of this investigation subspecific references w i l l be omitted. This fur-bearer i s indigenous to the mainland of the province. It has been successfully introduced orjjto= several Islands i n the Georgia S t r a i t as well as or^to Vancouver Island and onto Graham Island and Moresby Islands i n the Queen Charlotte Islands. The d i s t r i b u t i o n of the muskrat i s thus so extensive that there* are probably few areas of suitable habitat which i t has not at one time inhabited; However, maintenance and increase of population i n these areas i s l a r g e l y l i m i t e d by the adequacy of the habitat and i t s access to surrounding muskrat inhabited areas. Such adequacy 16 P L A T E 17 depends on the food p o t e n t i a l , both the type and the quantity. V GEOGRAPHICAL DIVISIONS FOR SURVEY For the purpose of t h i s investigation, the province has been divided into a r b i t r a r y areas using geographical boundaries. These areas, as shown i n Plate I, are as follows: A - area consists of that t e r r i t o r y bounded by the coastline of the mainland i n the west to 121° longitude i n the east. The south to north l i m i t s are 49° to 51° N. l a t i t u d e . B - area includes Vancouver Island and a l l other islands l y i n g west of the coast of A, with exception of the Fraser River delta islands and Nelson Island which are included i n A area. C - area i s defined as that t e r r i t o r y l y i n g north from 51© to 54° N. l a t i t u d e . It includes a l l coastal islands i n the west, except the Queen Charlotte Islands and extends to 119° longitude i n the east. D - area l i e s i n the south-eastern part of the province and i s bounded by the A l b e r t a - B r i t i s h Columbia border and the United States Inter-national Boundary. The western l i m i t i s 119° D D -3 £ S c a l e , 5 0 m i l e s t o 1 i n c h i f - r DISTRIBUTION O P T H E MUSKRA I n d i c a t e d bu 19 i n the northern part and 118° 30' i n the south. These l i m i t s were set i n order to include the Columbia River v a l l e y . E - area i s that t e r r i t o r y situated between A and-D. Its north-south l i m i t s are 51° and 49° N. l a t i t u d e , while i t s east-west l i m i t s are 118° | 30' and 121°. F - area includes the vast region of northern B r i t i s h Columbia l y i n g from 54° N. l a t i t u d e to the Yukon border and from Alaska to Alberta boundaries. G - area has been designated as the Queen Charlotte Islands. DISTRIBUTION IN EACH AREA A - area South-west B r i t i s h Columbia. Lower Mainland The major populations of muskrat i n t h i s area are confined to the lower mainland, Lulu Island, Sea Island and Fraser River Valley. Other reported smaller populations occur i n marshes around P i t t Lake, Seton Lake, Pemberton, Nelson Island, Sechelt Peninsula and Powell River. The greater part of the lower mainland area i s dyked land with t i d a l s a l t marshes. Most of the muskrats are bank-dwelling and are found along drainage ditches and / sloughs at the mouths of small creeks. Lulu Island and Sea 20 I F i g . 1. Looking north from B l u n d e l l Road along dyke and d i t c h . F i g . 2. Looking south from B l u n d e l l Road along dyke .and d i t c h L u l u I s l a n d (A-area) DRAINAGE DITCH HABITAT OF IHJSKRAT. • PLATE H a . Close-up of a p o r t i o n of the "bank h a b i t a t shown i n the above P i g . 1. L u l u I s l a n d (A-area) DRAINAGE DITCH HABITAT O P l.USKRAT. PLATE l i b . 22 F i g . 1. Kuskrat house composed of "bulrushes. F i g . 2. A f l o a t i n g piece of hoard forms t h i s d e f e c a t i n g post. Burnaby Lake ( A -area) 1IAESH HABITAT OF KQSERAT. PLATE H e . 23 Island are the p r i n c i p a l muskrat trapping areas of t h i s province. Just east of the 122° meridian, the Fraser River v a l l e y becomes narrow and the t e r r a i n mountainous. The Skagit Range of the Cascade Mountains forms at t h i s point a natural b a r r i e r to separate the i n t e r i o r and coastal muskrat populations. The Fraser V a l l e y population i s the natural range while the scattered populations along the coast are trans-plantations. The Seton Lake and ^ emberton Meadows probably represent migrations from the more i n t e r i o r ranges of the i Cariboo (C-area). The Nelson Island introduction was the only one f o r which records were available. In January 1926, three p a i r muskrats were l i b e r a t e d at Hidden Bay, Nelson Bay. A few years previous, an introduction was made at Green Lake, Nelson Island. By 1927, muskrats had spread over the entire i s l a n d and one was trapped at Ruby Lake on the main-land.- The following year, a f a i r stocking of muskrat was reported at the Pender Harbour lakes on Sechelt Penninsula. In 1929, another introduction which had heen made at Gordon Pasha Lake (on the mainland, north of Nelson Island) was reported to be spreading. B-area. Vancouver Island and Islands i n the Georgia S t r a i t The muskrat i s not indigenous to any parts of t h i s area. P r i o r to i t s introduction onfto Vancouver Island i n 24 1924, the records show that no muskrat was found i n the wild state. At t h i s time, under the d i r e c t i o n of the B.C. Game Conservation Board, muskrats were trapped a l i v e within the l i m i t s of the B u rnaby Lake Game Reserve (Vancouver). ^These were l i b e r a t e d at pointo that included Shaw Crook Game . Reserve (Vancouver) These were l i b e r a t e d at points that included Shaw Creek Game Reserve, Ucluelet, Jordan River, Port A l i c e , Hopkins Lake (Merville) and Comox. At the time of these introductions there were many suitable places on t h i s i s l a n d for muskrat and the Game Conservation Board intended to carry on t h i s work each year. This organisation, under the chairmanship of the l a t e M.B. Jackson, K.C., existed from 1918 u n t i l 1926. Storer (1938) had records of introduction of s i x muskrats each i n 1923 and 1924 at M i l l e r Creek, Forbes Landing, and Campbell River. In 1931 these l o c a l i t i e s were well populated and" crop damage by muskrats was reported (R.M. Stewart, B.C. Po l i c e , A t l i n , l e t t e r to Storer, December 4, 1931). In 1927, reports from the V i c t o r i a d i s t r i c t indicated that the muskrat was increasing and enlarging i t s range around Somenos Lake and Robertson River (Duncan). The next year, there was continued increase and spread throughout the lakes and fla/ts at Duncan, Lake Cowiohan and Saanich areas. Muskrats had also been seen at Port 25 Renfrew, thus migrating from the Jordan River area. In 1929, due to a rapid increase there were reports of a g r i c u l t u r a l damage by muskrats. The following year 9,000 pelts were taken. Also, i t i s to be noted that seven years following i t s , introduction, the muskrat i s reported as a nuisance i n southern Vancouver Island. In 1935, following an open season, the f i r s t record of a noticeable decrease took place. During the years that follow, there have been continued migrations into surrounding suitable areas. Aside from these o f f i c i a l transplantations, there have been introductions made by fur-farming interests f o r which there are no available records. If the interest f a i l e d , ' t h e animals were l i b e r a t e d to provide a new focus of introduction. I t was i n t h i s manner that the muskrat became established on c e r t a i n islands i n the Georgia S t r a i t that include Salt,Spring, Quadra, Thurlow, and Denman Islands. The transplantation onto the l a s t named is l a n d took place i n 1935 (T. Pearce, Gourtenay, June 1933 to Storer). It i s possible that the Salt Spring Island population represents a migration from that at Duncan. C - area, Central B r i t i s h Columbia. The muskrat i s widely d i s t r i b u t e d throughout t h i s area. F^ea F i g . &, It i s noted that the greatest number occur on suitable creeks and marshes on the C h i l c o t i n River 26 and south of Quesnel, west of the Fraser River. East of t h i s r i v e r , they are most abundant i n the "lakes region", south-east of Williams'Lake. Muskrat are also present, but scarce west of the Cascade Mountains. They are rare i n the high altitude-deep snow country i n the eastern part of t h i s area. A c e r t a i n amount of muskrat are trapped along the northern l i m i t s i n the Prince George and Vanderhoof d i s t r i c t s . J.A. Munro (1987) reported that there were no places i n t h i s northern area as favorable for muskrat as some l o c a l i t i e s i n southern B r i t i s h Columbia (E-area). According to Munro, "the waters vary i n elements making up the food p o t e n t i a l and some could be c l a s s i f i e d as sub-marginal." PLACE AREA HOUSES T i l l y Lake (Tatla Lake region) 2 x 1.5 mi. 8 Small marsh (Big Creek region) 1 x 0.25 mi. 0 Exeter Lake (100-Mile House) 1 x 0.5 mi. 7 Edmonds Lake ( do.. ) 1 j x 0.5 mi. 12 4 small lakes, each (Bella Coola) ' 1 A. 8 x i mi. 4 3 lakes & marsh (Chilako River) 2 sq. mi. 25 Punt'chesakut Lake (Quesnel) 2 x §• mi. 1 Dragon Lake (Quesnel) 3 i x 1 mi. 3 TABLE 2 HOUSES ON INDIVIDUAL AREAS. The above table indicates a few small areas with 27 the number of occupied houses on each f o r 1945. This number i s said to vary, often greatly, from one year to another* There i s apparently adequate reason to believe that the beaver-muskrat association furnishes a source of population maintenance of the l a t t e r . Several trappers have found that as the beaver declines so does the muskrat. D - area. Kootenay and Columbia Rivers Valleys. In t h i s area, the majority of muskrat are trapped from Golden south, along the marshes of the Columbia River to i t s source at Columbia Lake, an area of about 110 sq. mi. Except for. a small population along St. Mary's River, near Kimberley, muskrat are scarce i n the Pernie D i s t r i c t . Reports indicate that there very few i n the Arrow Lake d i s t r i c t while they seem f a i r l y abundant i n the Slocan d i s t r i c t . In the Kootenay Lake d i s t r i c t , muskrat are trapped along the Duncan River i n the north while a few are found at the south end near Creston. In the Kootenay National Park, muskrats have been seen i n S i n c l a i r Creek and i d e n t i f i e d by tracks along the shores of Dog Lake and Dolly Varden Creek Valley (Munro & Cowan). . . . ;. This part of B r i t i s h Columbia i s of an extremely rugged t e r r a i n . Most of the lakes and streams are rocky and g l a c i e r - f e d with shores unsuitable f o r a marsh habitat. E - area. South Central B r i t i s h Columbia. In the Okanagan d i s t r i c t of t h i s area are found 28 some exceedingly suitable muskrat marshes. In f a c t , the bulk of muskrat p e l t s from t h i s area are co l l e c t e d from the Okanagan Lake south to the Osoyoos Lake along the Okanagan River. Other l o c a l i t i e s where small muskrat catches are taken include the southern regions of the Similkameen River, Lac l e Jeune (20 mi. south of Kamloops), and Pennask Lake and Nicola Lake d i s t r i c t s , both" near M e r r i t t . The Princeton-Hedley D i s t r i c t i s not a muskrat-producing area. The following table i l l u s t r a t e s a few reported populations that occur outside of the Okanagan D i s t r i c t . PLACE AREA HOUSES' Garcia Lake (10 mi. N.E. Merritt) . 30 A. 1 House & 6 bank dens Campbell Lake (20 mi. S.E. Kamloops) 100 A. 6 White Lake (20 mi. S.E. Kamloops) 40 A. 6 Lac ~le Jeune, west end 25 A. 8 Table 3 - Small populations that t y p i f y E - area. E - area. Northern B r i t i s h . Columbia. In t h i s expanse of t e r r i t o r y north of the 54° Latitude, f a i r returns were received from the 'outline questionnaire' considering the i s o l a t i o n of many places. From 10 p o s i t i v e and 18 negative returns, the d i s t r i b u t i o n map of the muskrat i n t h i s area was compiled. (Figi 6) Muskrat colonies are generally small. Some trappers reported a few muskrats i n beaver ponds i n the f a l l , but the following spring they had disappeared. 29 Apparently the most favourable muskrat areas are those just north of Prince George and the Fort Fraser D i s t r i c t s . The l a t t e r i s a continuation of the -muskrat area around Vanderhoof i n C - area. Frederick Velten, trapping along the Dease River, reported considerable muskrat on h i s 22 mile t r a p l i n e . 118 pelts were collected i n 1946. A few are present along the Stikine River, but the s i l t e d condition of t h i s r i v e r i s unfavourable to the species. Swarth, i n 1922, reported that muskrats were scarce along i t s entire length. They are also scarce i n the coastal d i s t r i c t from A l i c e Arm to Prince Rupert. They are absent i n marshes along the Copper River but present i n the marshy south end of Lakelse Lake. In t h i s area they are mainly bank-dwelling muskrats. I. MoT. Cowan, i n a b i r d and mammal survey of the Peace River D i s t r i c t , reported muskrats i n three small lakes i n the v i c i n i t y of Fort St. John. . .-In north-west B r i t i s h Columbia, i n the A t l i n D i s t r i c t , a few are reported on small marshy areas of Tagish and- T e s l i n Lakes. They are not trapped as apparently unfavourable conditions prevents any population increase. There are possibly many similar small muskrat populations throughout F-area, but t h e i r scant numbers makes trapping impractical. 30 PLACE AREA HOUSES Lake, on Morice River (Topley) l x l mi. 5' Mosquito Lake (Dease River) 1 x % mi. 30 push-ups Smith Lake (Dease River) 1 x £ mi. 22 " Goose Lake (Dease River) 1 x.£ mi. 6 " Marsh #1 (Port Eraser) 40 A. 20 Marsh #2 (Port Fraser) 160 A. 25 Table 4. Examples of Small Populations i n F - Area. The above table i l l u s t r a t e s the d i s t r i b u t i o n i n some reported areas. In many places, the muskrats are bank-dwelling,' hence accurate figures were not obtained. G - area. Queen Charlotte Islands. The muskrat on these islands i s l i m i t e d to Graham Island and Moresby Island, on the former, according to H a l l e t t (Pritchard, 1934), 15 muskrats were l i b e r a t e d between 1924-1925. In A p r i l 1933, they had spread 30 miles over rough country and were reported causing damage to dykes and ditches.. A B C I) E F G FUR-BEARER Pos. Neg. Pos. Neg. Pos. Neg. Pos. Neg. Pos. Neg. Pos. Neg. Pos. Neg, MUSKRAT 10 —• 5 — 22 12 # 7 • - / - 3 BEAVER 2 1 0 1 14 1 10 0 7 1 7 9 0 -COYOTE 2 1 0 0 11 6 4 5 6 4 6 7 0 -FISHER 0, 0 0 0 6 1 0 0 0 0 7 4 0 -FOX 2 2 .0 0 11 1 1 1 0 1 . 7 10 0. -LYNX • 3 0 0 0 7 3 6 6" 6 2 4 6 0 -MARTEN 2 5 2 4 7 3 8 8 4 1 7 11 2 -MINK • 7 6 4 7 17 1 12 8 8 8 8 2 0 — OTTER ,. 2 1 0 4 4 . 0 1 0 5 0 4 3 1 -RACOON 4 4 5 8 0 0 0 0 0 0 0 0 0 -SKUNK • 1 2 1 o 1 0 2 2 1 0 0 0 0 -SQUIRREL 2 2 1 1 14 5 6 5 5 3 6 7 0 -WEASEL 3 3 2 2 16 5 9 7 6 3 7 12 1 -WOLF 1 0 0 0 2 0 0 0 0 0 6 4 0 • -WOLVERINE 1 0 0 0 0 0 0 0 0 6 3 3 0 -TOTAL 10 7 5 11 22 8 13# 11 7 4 10# 18 3 0 SUM FOR AREA 17 16 30 24 11 28 3 TABLE 5. DISTRIBUTION OF THE FUR-BEARERS ON 127 REGISTERED TRAPLINES THROUGHOUT BRITISH COLUMBIA. § WHERE MUSKRAT' WAS INDICATED AS 'FEW' OR »SCARCE' , THE POSITIVE RETURN RECEIVED HALF VALUE. 32 i i J • i t 1 i t M 4 j If tit ^1 l-t ) 1 I ..It * 5 <* * i« 3 ? V] O PLATE III OTHER PUR-BEARING ANIMALS ON THE SAME REGISTERED TRAPLINE AS r RECORDED PROM 73 POSITIVE RETURNS OP THE 'OUTLINE QUESTIONNAIRE 1. 33 In t h i s connection, A.L. Pritchard (1934) suggests, "Was the introduction of the muskrat i n the Queen Charlotte Islands unwise?". At t h i s time, they were reported as depleting the pink salmon f r y at the experimental counting screens. In recent years, there has been l i t t l e mention of the population on Graham Island. However, i t i s presumed that the population has spread around Massett Inlet and the Rivers entering i t . Records of other o f f i c i a l muskrat transplantations are not available. However, private introductions have been completed. George W. Leary, Port Clements, introduced the muskrat i n 1929, onto about 100 acres of meadowland. This area i s divided into four sloughs, about 25 acres each, with the T l - e l l River running through the center. In 1934, his f i r s t trapping season netted over 200. pelts.. Since 1936, the muskrats have been less numerous and the 1946 trapping season netted only 116 p e l t s . Mr. Leary believes that the food p o t e n t i a l i s s u f f i c i e n t to maintain only the existing population. He has also found that they breed l a t e r i n the spring and produce smaller L i t t e r s than they do i n the southern parts* of the range. POSITION OP THE MUSKRAT AS A PUR-BEARER Plate 3'-, based on the 73' p o s i t i v e returns of the •outline questionnaire' shows that mink, weasel and beaver respectively are the fur-bearers appearing most frequently. 34 • on the same registered trap-line. When t h i s graph i s compared with the table on the royalty c o l l e c t e d from p e l t s of fur-bearing animals i n the Report of the P r o v i n c i a l Game Commission, 1945, i t i s found that with the exception of squirrel.which i s f i r s t , the order of the f i v e most important fur-bearers i s i d e n t i c a l . Graphs 1 to 7 inc l u s i v e i l l u s t r a t e the r e l a t i o n of • i muskrat to other fur-bearers i n each area throughout B r i t i s h Columbia. These Graphs were derived from the l i s t of animals trapped on the 73 registered t r a p l i n e s which contained muskrat. From t h i s l i s t , f o r each area, the percentage of each fur-bearer was calculated using the muskrat as 100$. These figures were then gr a p h i c a l l y represented. This formed a convenient means fo r a q u a l i t a t i v e comparison of the f u r -bearing animals i n the d i f f e r e n t areas of t h i s province. For A - area, Graph 1 shows that mink and racoon are the next most important mammals c o l l e c t e d . The negative returns, Table 5, show that mink and racoon form the main c o l l e c t i o n . In B - area, : Graph 2, racoon i s c o l l e c t e d to a similar degree as muskrat while mink, marten and weasel are next i n importance. Non-muskrat. areas produce mainly mink and racoon. From Graph 3, i n C - area, the mink, weasel and beaver are found on muskrat /tr a p l i n e s . The coyote, weasel and s q u i r r e l are produced more i n non-muskrat areas. 35 . G R A P H S 1 92 93 and 4 • T H E R E L A T I O N O F M Q S K R A T T O O T H E R F U R - B E A R E R S I N A R E A o GRAPHS 5,6 and 7 THE RELATION OP MJSKRAT TO OTHER FUR-BEARERS IN AREA. 37 1:.' In D and E - areas, as noted i n Graphs 4 and 5, the ;mink and beaver are placed with the muskrat. In non-muskrat areas of D -area, marten, mink and weasel are most evident while i n E - area, the coyote, weasel and s q u i r r e l are the p r i n c i p a l fur^bearers. In F - area, according to Graph 6 , mink are trapped to the same degree as muskrat. From the negative returns, i t was found that weasel, mink marten and fox form the greatest pelt returns; beaver i s also collected to a lesser extent. Among other fur-bearers trapped on Graham Island of G - area are marten, otter and weasel. •si -38 DISEASES AND PARASITES OF THE MUSKRAT From October 15, 1944 to May 15, 1947, 202 muskrats were examined f o r the presence of diseases and parasites. L carcasses received during the l e g a l trapping„were skinned, hence external parasites could not be enumerated. The follow-ing specimens were c o l l e c t e d outside the l e g a l trapping season: A l to. A14, October 1944; A34 to A41, summer of 1945; B7 to B9, November 1946 and E33, May 1947. The l e g a l trapping season f o r muskrat varies throughout B r i t i s h Columbia. In the lower mainland of A-area and B-area, i t i s a winter season from December 1 to February 28. Throughout the remainder of the province, muskrats are trapped i n the spring from March 15 to May 15. In the more northern l o c a l i t i e s , trapping sometimes does not begin u n t i l the end of May, as i t i s often d i f f i c u l t p r i o r to the cessation of freeze-ups. Thus the seasonal nature of t h i s investigation offered s l i g h t opportunity f o r a comparison study of interseasonal incidence. As stated previously, protozoan parasites were not studied due to the usually advanced state of decomposition of the carcass.. However, in' the l i g h t of the absence of t y p i c a l protozoan lesions, i t may be assumed that pathogenic protozoa were absent in the carcass examined. It i s noted from T a h i t i that there i s an absence of previous study on protozoan parasites of the muskrat. 39 This may he a t t r i b u t e d to the f a c t that most p a r a s i t o l o g i c a l studies on the muskrat have been performed on caracsses sent for examination. The present survey revealed that the muskrat i s infected by two d i f f e r e n t pulmonary infect i o n s as well as being prone to a tumorous condition, i n f e c t i o n of wounds and i n t e r n a l abscesses. I t i s host to eleven species of helminth parasites, "gsa of these, have been previously recorded as i n f e c t i n g the muskrat, while a species of Acanthocephala appears to be a hew record f o r t h i s host. R Sa-Cond spa-cta,s o-f Ccstoc/e. 'S au r><cu) record -for- -fcA<z> JV.u S/t ha,~t. DISEASES AND PATHOLOGIES  Pulmonary Infection Four muskrats from two widely separated l o c a l i t i e s were found to be affected by a pulmonary i n f e c t i o n . Two of these specimens, A42 and A61 were from Lulu Island while E13 and E26 came from Rutland F l a t s and M i l l Creek i n the Okanagan.. Description of the Lesions. In a l l cases, similar lesions were observed. The i n f e c t i o n i s apparently one of the blood since a l l lobes of the lung were equally affected. The'degree of i n f e c t i o n i s indicated by the density of the l e s i o n s . The following description was taken from specimens that had undergone at le a s t 24 hours decomposition.- This change was more advanced i n specimens E13 and E26, because they were not received 40 u n t i l at least 48 'hours after death. The lesions appeared as petechial greyish-white c i r c u l a r areas on the surface of the lung. Where several areas had coalesced, the area appeared whitish and r o o t - l i k e surrounded by a paler grey area. Each c i r c u l a r area contained one spherical white capsule, which could be e a s i l y dissected from the surrounding t i s s u e . A coalesced area would contain several capsules. These capsules were a f a i r l y uniform s i z e , varying from 0.24 to 0.27 mm. i n diameter. If a capsule, was placed between a microscopic s l i d e and cover-s l i p , considerable pressure was required to break the w a l l ; whereupon i t l i b e r a t e d thousands of coccus-like organisms. When stained with methylene blue, each organism was composed of a homogenous f i n e l y granular suhstance. The general condition of the animal was good, the f l e s h was i n good colour, the other organs were normal and parasitism was usually normal. Histopathology of the Lesions. A section of the lung from A42 was f i x e d i n Formol-alcohol and stained with.Harris-haemotoxylin and counter-stained with al c o h o l i c eosin. The lesions were di s t r i b u t e d throughout the lung tissue i n a density similar to that observed onvthe surface. Each l e s i o n involved l i t t l e t i s s u e , being compact within i t s capsule wall inside an alveolus. The lung tissue was not stimulated to produce any further walling o f f . The tough 41 F i g . 1. Photomicrograph showing the p o s i t i o n and w a l l of a pulmonary l e s i o n from the u n i d e n t i f i e d pulmonary i n f e c t i o n . P i g . 2. Photomicrograph showing H. octocoronata embedded be tween the v i l l i i n the small i n t e s t i n e . PLATE XI 42 capsular wall was composed of a compact homogenous anuclear substance .laid down i n a double layer. It sectioned poorly and appeared to be a product of the causative organism. The i n t e r n a l layer absorbed the'haemotoxylin s t a i n while the external layer absorbed the eosin s t a i n . The contents of the capsule stained haemotoxylin, Plate 2PT, Figure 1. Experimental studies to i d e n t i f y the causative organism. The lungs of the diseased muskrats, E13 and E26, 0 were kept fresh by freezing i n p h y s i o l o g i c a l s a l i n e . On March.21, 1947, 65-70 capsules were dissected from the lungs of E13. These capsules were washed and centrifuged several times i n s t e r i l e p h y s i o l o g i c a l s a l i n e , then crushed i n a mortar. This u n f i l t e r e d material was injected into s i x rabbits as follows: AMOUNT OF RABBIT NO. INJECTION METHOD 16 1.5 cc. intravenous .21 0.7 cc. intravenous 10 0.4 cc. intrath o r a c i c 25 0.4 cc. intrath o r a c i c 5 0.5 cc. (app.) intranasal 6 1.0 cc. (app.) intranasal On May 2, 1947, rabbits #16, #21, #25 and #6 were k i l l e d and examined. None of these rabbits showed t y p i c a l pulmonary lesions l i k e those found i n the muskrats. •'• Rabbit #21, however, showed six pinhead sized whitish lesions on the surface of the l i v e r . These lesions 43 could be removed from the surrounding tiss u e i n a manner, simi l a r to the o r i g i n a l pulmonary lesi o n s . The presence of oocysts i n a microscopic smear of these:lesions proved them to be coccidia. Should these l i v e r l esions have been a r e s u l t of the o r i g i n a l pulmonary organism from the muskrat, and since rabbit #21 received the smaller does, i t would have been expected that rabbit #16, which received twice the dose, be s i m i l a r l y infected. This was not the case. Therefore, i t was concluded that tho c o c c i d i a l i n f e c t i o n of rabbit #21 was independent of the attempted experimental i n f e c t i o n . 1/flhen i t was found that the rabbits examined did not contract the i n f e c t i o n , post-mortem of the other rabbits seemed unnecessary. Further experimental work was conducted on the albino r a t . On May 21, 1947, two male r a t s , one l e s s than si x months old and the other about a year were - injected i n t r a t h o r a c i c a l l y with a strong 1 cc. s t e r i l e p h y s i o l o g i c a l saline suspension of crushed capsules. It was brought to the attention of the investigator that the older rat was infected with tuberculosis. On June 4, 1947, these rat s were k i l l e d and examined. The t y p i c a l tubercular lesions were present i n the older animal. The pulmonary systems of both animals were placed i n p h y s i o l o g i c a l saline and allowed to macerate. After four hours, scattered f o c i of i n f e c t i o n were found to be present in both systems. These lesions were sim i l a r to those present 44 i n the muskrat and d i s s i m i l a r to the tubercular l e s i o n s . The younger rat appeared more heavily infected than the older one. These lesions were smaller than those present i n the muskrat. Immediately following death, they are masked by the white a i r - f i l l e d alveolae and hence become prominent only upon collapse of the alveolae. At the time of writing, further experimental work i s i n progress to i d e n t i f y the causative organism.^ Death due to tumorous condition. May 10, 1945, Dr. I. MoT. Cowan found a muskrat at Burnaby Lake Game Reserve that had been dead f o r 3 - 4 days. Examination revealed the presence of three large tumors: one on the side of the neck and two i n the a x i l l a r y region. The lungs had 5 scattered f o c i of i n f e c t i o n , which ranged from 2 - 5 mm. diameter. I t was apparent that death was caused p r i m a r i l y by the tumorous condition; the pulmonary . condition probably was secondary. Histopathology of the tumors was d i f f i c u l t to interpret-due to extensive post-mortem decomposition. There appeared to be howeverjaprurulent center with a fib r o u s connective tissue capsule. Connective tissue had also penetrated into the center of the l e s i o n . The gross appearance of the f i x e d pulmonary l e s i o n s leads the investigator to believe that they are probably tuberculous i n nature. They resemble c l o s e l y the t y p i c a l tubercular lesions of the albino r a t that r e s u l t from 45 i n f e c t i o n by Corynebacterium rodentium. The histopathology was d i f f i c u l t to follow due to the advanced decomposition that preceded f i x a t i o n . Other minor pathologies. These lesions were small and appeared, i n general, not to i n t e r f e r with the health of the infected animal. MUSKRAT NO. REGION DESCRIPTION CE7 I-transverse colon several d i s t i n c t l y separate ectymotic hemorrhagic areas. I n t e s t i n a l w a l l scrapings revealed no protozoan i n f e c t i o n . D4 mid-lumbar region oval, walled-off, c y s t - l i k e l e s i o n , 25 mm. x 13 mm. containing yellow pus. A Giemsa stained smear revealed only lymphocytes and polymorphonuclear leukocytes. The lumbar lymph nodes were s l i g h t l y enlarged. D6 . v e n t r a l lumbar region small elongated c y s t - l i k e node, 10 mm. x 5 mm. s i m i l a r i n appearance and consistency as the l e s i o n of D4. No enlargement-of lymph nodes. TABLE 6.1 Minor Pathologies. The above table i l l u s t r a t e s the lesions that occurred, that were apparently not a r e s u l t of wounds. Pathologies due to wounds. Prom time to time, muskrats were found with abscesses that had developed following a wound. These abscesses apparently did not impair the animal's s u r v i v a l . Often these wounds l e f t no external evidence. , The wound 47 healed externally while an abscess developed i n t e r n a l l y . This followed various types of wounds; that l e f t when a foot was l o s t following I an excape from a trap, Plate 17, i , • and wounds as a r e s u l t of i n t r a s p e c i f i c s t r i f e . MUSKRAT NO. REGION DESCRIPTION OF LESION A55 A63 A70 l e f t fore limb The bones had become infected due to the loss of the f o o t . The A79, a x i l l a r y lymph gland i s usually enlarged. C18 l e f t Following a lung puncture, a posterior permanent adhesion to the c o s t a l lobe of . lung wall resulted. A l l external evidence had healed and there was no evidence of fractured r i b s . Histopathology revealed that the abscess had one primary focus and two secondary f o c i . It was com-p l e t e l y walled off by fibrous connective t i s s u e . E33 it " l e f t An abscess had developed at a abdominal point where the diaphragmatic wall near diaphragm muscle meets the l a t e r a l abdominal wa l l . It was 15 mm. long and oval' shape and contained greenish-yellow pus. Also, at: t h i s point the stomach was permanently adhered to the abdominal wall. The abscess developed following a stomach puncture. External evidence had healed.  48 TABLE 7.: Description of Lesions as a r e s u l t of mechanical injury. REPORTED DISEASES OF THE MUSKRAT IN BRITISH COLUMBIA Analysis of the reports from game-wardens and trappers throughout t h i s province regarding diseases of muskrat are l i m i t e d mainly to infections r e s u l t i n g from i n t r a s p e c i f i c f i g h t i n g and trapping wounds.- These wounds become, infected and as a r e s u l t abscesses develop. In a few instances, a s p e c i f i c outbreak of disease has been reported. In A - area, at Port Goquitlam approximately 3 i n 100 muskrats trapped have infected wounds following the loss of a foot i n a previous trapping. At Lulu Island, i n the same area, two animals with externally infected wounds were trapped i n December, 1946. Both of these muskrats were young, probably from 1946 l i t t e r s ; In B - area, at Duncan, about 10$. of the muskrats are affected by"external abscesses, according to two independent reports. In C - area, at ! Williams Lake and Kleena Kleene, trappers indicate that most infected wounds may be att r i b u t e d to i n t r a s p e c i f i c s t r i f e . Such wounds are i n evidence during the spring sexual f i g h t i n g . Hence, pelts taken at t h i s time are often valueless. Internal abscesses similar to those found i n t h i s survey were reported from Tatla Lake D i s t r i c t . 4 49 In D and E - areas, there were reports "of wide-spread occurrence of abscesses among the muskrats. In the spring of 1946 about 65$ of those .trapped around the Nicola River, i n late spring, showed infected f i g h t i n g wounds. In 1937, i n the v i c i n i t y of Briseo, i n D - area, the muskrat catch was scant. Those co l l e c t e d were heavily infected with b o i l s . This condition disappeared i n the following years. H. Tyler reported that muskrats at the southern end of Windermere Lake were also s i m i l a r l y a f f l i c t e d . It was noted that t h i s condition was more prevalent i n those that b u i l d among the bulrushes. In F - area, the only wounds that a f f e c t the muskrat populations are those received during•intra-s p e c i f i c f i g h t i n g . In the Stikine River D i s t r i c t however, trappers have caught muskrats, and also found them dead infected with abscesses at the sides of the lower jaw. In 1938, at the Queen Charlotte Islands, Mr. G.W. Leary picked up some muskrats dead." Examination of the carcasses revealed no apparent cause of death. This was the only report of disease among the muskrat populations i n G - area. i Analysis, of Wounds. I t i s apparent from the reports and the carcasses examined that there i s a high tolerance f o r wounds due to i n t r a s p e c i f i c s t r i f e . Such wounds do occasionally become infected. However, they heal 50 externally and the organisms become concentrated inside a connective tissue capsule. The general health of the animal i s not affected. This was i l l u s t r a t e d i n muskrats C18 and E33* where punctures of i n t e r n a l organs had taken place. Although an adhesion and an abscess had formed, the wound had healed externally. Also, the animals appeared i n good health. Frequently, a trapped muskrat w i l l escape with the r e s u l t i n g loss of a foot. This wound w i l l often heal completely with no i n f e c t i o n . There are instances how- ; ever, when such a wound w i l l become infected. This i n f e c t i o n invades the b.one and produces an o s t e i t i s . Such inflammation usually centers around the injured j o i n t s , which become dislocated i n the animal's f i g h t for freedom. The lymph glands of..,the region also become .infected. In t h i s survey, four muskrats from A - area were thus injured. A63, a male adult of an 1946 l i t t e r , was trapped on January 12, 1947. As shown i n Plate IY, P4g. & the entire lower humerus was.involved i n the o s t e i t i s . This i n f e c t i o n had apparently developed since December 1, 1946, the beginning of the trapping season. Analysis of s p e c i f i c diseases and t h e i r e f f e c t s . Actual mortality from disease i s d i f f i c u l t to ascertain i n the muskrat. This s i t u a t i o n i s e s p e c i a l l y 51 d i f f i c u l t to analyse when "the investigatorjis dependent on reports of i t s occurrence and not on personal observations. It i s evident however, from the carcasses examined that t h i s fur-bearer i s affected by at l e a s t two s p e c i f i c diseases. Reports from the trappers indicate a possible t h i r d s p e c i f i c disease. The tumorous condition of the dead muskrat at Burnaby Lake i s probably more of a developed'Condition than a diseasecthat could be disseminated through a population. The two respiratory infections however, appear to be l i k e l y diseases that might decimate a population. The pulmonary condition present i n both A and E - areas i s a condition that may be spread by d i r e c t contact between diseased and healthy animals. This disease appears to be s i m i l a r to that described by T. Warwick i n 1934, which was prevalent among muskrats i n Shropshire. His description of the lesions resembles that found i n this survey. Also, i n both cases, the animals appeared healthy. It i s i n the experimental studies that these two infe c t i o n s seem to d i f f e r . Warwick found that the rat d i d not contract the disease. However, he omits s t a t i n g the period that lapsed between i n j e c t i o n and autopsy of the experimental animals.. In t h i s experimental work, i t was found that the rat was infected following two weeks incubation period. The lesions were, small and did not become evident u n t i l after maceration of the t i s s u e . TABLE 8. FREQUENCY DISTRIBUTION OF THE ADULT 'HELMINTH PARASITES' OF THE MUSKRAT IN BRITISH COLUMBIA A D UL T CLASS P A R A S I T E S P E C I E S REG-ION A 8 0 ~ ~ — INFECTION SPEC. AY..„,;EXT:J A V S T Z 5 L ——————B 9——————— INFECTION SPEC. C 64 INFECTION SPEC. EXT. NO. <& D 16 INFECTION SPEC. M M NO. <& E33 INFECTION SPEC. T R ECHINOSTOMUM . . COALITUM V STOM. INT. CEC. COL. 3.2 20.7 5.4 1-13 1-130 1-27 15 47 11 18.75 58.75 13.7 4 230 1 11.1 9.8 2-23 7 10.5 7.3 2.-13 3 18.6 3.5 1-6 2 6-1 E M ECHINOPARYPHIUM CONTIGUUM STOM. INT. CEC. COL. - -- - ---- 24.4 107.1 16.3 12.0 1- 61 6-240 2- 51 2-43 5 13 7 5 7.5 19.5 10.5 7.5 - -- • -- - - -A T QUINQUESERIALIS QUINQUESERIALIS STOM. INT. CEC. COL. 1.5 3.3 69.8 1-2 1- 7 2- 298 2 3 34 2-5 . 3.75 42.5 76.8 2-201 8 88.8 121.3 7-376 27 40.5 85.3 4-304 15 93.0 89.0 1-850 15 45.5 0 D NOTYCOTYLUS URBAN ENS IS STOM. INT. CEC. COL. 13.7 3-38 13 16.25 2.5 2-3 2 22.2 13.3 10 2-128 1 23 1.5 34.5 13.5 15 1-69 1 12 6.2 74.4 1-0 1 2 6-1 A • PLAGIORCHIS PROXIMUS STOM. INT. CEC. COL. - 1-165 2 2.5 ---- . . 30.8 1-109 20 mm 30-0 54-0 4.5 4-233 2-7 11 2 68.2 12.4. 17.6 1-74 13 39.4 CESTODA HYMENOLEPIS SP. STOM. INT. CEC. COL. 3.7 59.5 1-7 1-250 3 40 3.75 50.0 2 1-3 5 55.5 6.0 1-18; .7 10.5 6.0 1-16 3 18.6 7.6 1-15 5 15.2 _ — — _ _ _ mm mm _ _ ' _ - _ _ _ NEMATODA ' CAPILLARIA RANSOMIA STOM. INT. CEC. COL. 5.0 5.4 2 5 1-27 2 1 9 1 1.25 11.25 1.25 - 6 1. 11.1 . 1 1 5 7.5 6.3 2-10 4 24.8 10.3 1-55 42.4 ACANTHO-CEPHALA POLYMORPHUS SP'. STOM. INT. CEC. COL. - - - - 1.8 1-3 4 6.4 - - - - - - .-)1 t o 53 Warwick i d e n t i f i e d the causative organism as a haemolytic streptococcus that i s r e l a t e d to other streptococci.of animal o r i g i n . This organism was highly pathogenic to mice. The causative organism that i s producing the i n f e c t i o n i n the B r i t i s h Columbia muskrats has not yet been i d e n t i f i e d . Experimental studies are s t i l l i n progress. In the discussion on the mortality produced by t h i s i n f e c t i o n , Warwick states that the animals were found when population densities were rather low, hence i t i s u n l i k e l y that carcasses of dying animals would be frequently found." He believed that mortality must have been f a i r l y widespread. PARASITES Table 8, i l l u s t r a t e s the d i s t r i b u t i o n of the adult helminth parasites of the muskrat i n B r i t i s h Columbia. Besides these parasites which were found i n more than one carcass, there were found a few specimens of male T r i c h u r i s  opaca i n the intestine of a muskrat from Lulu Island. Two species of l a r v a l cestodes, Taenia taeniaformis and Clado-taenia sp., were found i n the l i v e r as cysts. The l a t t e r also occurred i n a cyst at the base of the mesentry. Discussion of the Parasites. Trematoda Echinostomum coaliturn :Barker 1915 Family Echinostomidae Looss 1902 Subfamily Echinostominae Looss 1899 Genus Echinostomum Rudolphi 1809 54 Status This species was f i r s t described as a parasite of the muskrat by Barker i n 1915. Accordingly, i t may be distinguished by a "well defined reniform c o l l a r " consisting of 37 spines. These are arranged i n an alternate row of £7 large spines on the rim and 5 spines on each lappet. P.O. Beaver (1937) while completing a study of Echinostomum revolutum (Proelich) reduced 16 other named species including E. coalitum to synonymy with E. revolutum. He inferred that p h y s i o l o g i c a l differences i n d i f f e r e n t species of hosts would often lead one to believe that a new species -had been found. Since the investigator has not had the opportunity of examining many specimens of E. revolutum which t y p i c a l l y i n f e c t s aquatic b i r d s , the o r i g i n a l s p e c i f i c a t i o n - ' E . coalitum from the muskrat' has been used i n t h i s study. The specimens collected were t y p i c a l f o r the species, hence redescrip.tion i s unnecessary. Infection a There was a wide range of i n f e c t i o n by E. coalitum. It rated the highest incidence i n A - area, where i n f e c t i o n averaged 58,75% i n the small in t e s t i n e with 18.75$ and 13.7$ i n the stomach and cecum respectively. It i s i n t e r e s t i n g to note the v a r i a t i o n i n i n f e c t i o n i n the d i f f e r e n t l o c a l i t i e s within a given area. From the following table, i t may be observed that although Burnaby 55 Lake muskrats presented a 58.3$ i n f e c t i o n , i t r e g i s t e r e d an. average incidence of 35.1 worms. This i s compared with a 79.1$ i n f e c t i o n by an average of 10.3 worms at Lulu Island. These two l o c a l i t i e s are approximately 20 miles apart. Had more examinations been completed from the Sea Island muskrats, i t i s possible that the i n f e c t i o n would compare c l o s e l y to that of Lulu Island. PLAGE INFECTION '. TOTAL , $ TOTAL INFECTION INFECTION AVERAGE INFECTION Burnaby Lake 24/41 58.3$ 843 35.1 Lulu Island 19/24 79.1$ 196 10.3 Sea Island 1/7 14.3$ 3 -P i t t Meadows 2/4 50.0$ 50 25.0 Clayburn • I A 25.0$ 4 -Table 9. Comparison of i n f e c t i o n i n l o c a l i t i e s i n A - area by E. coalitum. Although only one muskrat from B - area was infected, i t contained 230 i n d i v i d u a l s . As may be noted i n Table 8,only small percentage infections were recorded i n C, D and E areas. In C - area, only muskrats from Williams Lake were infected. In D -area, only carcasses from Radium were p a r a s i t i s e d . Discussion According to Table 1, E..coalitum has been recorded three times since Barker's o r i g i n a l record. Swales (1933) reported i n a review of Canadian helminthology, Echinostomum sp. / 56 from the muskrat i n Alberta. P.C. Beaver (1937) includes several records from eastern North America of the species E. revolutum. Echinoparyphium contiguum Barker and Bastron Family Echinostomidae Looss 1902 Subfamily Echinostominae Looss 1899 Genus Echinoparyphium Dietz 1909 Status This i s another species of trematode reported i n F. D. Barker's p u b l i c a t i o n of 1915. I t was o r i g i n a l l y described as a"small trematode, 3.3 to 4.3 mm. The c o l l a r has 37 spines arranged i n alternate rows of M o r a l and 15 aboral spines on the rim and one set of 4 on each lappet." P.O. Beaver (1937) disputes the v a l i d i t y of the above description and states that the specimens i d e n t i f i e d as Echinoparyphium contiguum i n the B.A.I, of the U.S.D.A. "have more than 37 spines, having 45 i n some and 47 i n others." On the other hand, Barker and N o l l describe some specimens as belonging to the species Echinostomum callawayensis which have 'Ha c o l l a r armed with a double row of a l t e r n a t e l y arranged spines varying i n number from 37 to 41, 31 to 33 on the rim and 2 to 5 on each f l a p . " There has been only one report of Echinoparyphlum sp. from the muskrat since 1915, that by Lav/ and Kennedy i n 1932. Of t h i s record Beaver, states that "unfortunately the cephalic spines are not included i n the description, and no specimens could be procured." 57 As a r e s u l t of the apparently c o n f l i c t i n g description hy Barker and the absence of more recent study on t h i s species, i t i s pertinent that a d e t a i l e d description be presented at t h i s time from the specimens at; hand. Description This composite des c r i p t i o n i s based on a series of specimens c o l l e c t e d from muskrats i n the YiTilliams Lake D i s t r i c t of C - area. These specimens were prepared f o r study according to the technique outlined on page 14. In an i n f e c t i o n , the size of the worms does not vary greatly. The length averages about 2.8mm. while the width.at the l e v e l of the acetabulum i s 0.4 mm. The width at the l e v e l of the posterior testes i s 0.3 mm. The acetabulum i s situated about one-third of the t o t a l length posterior to the. o r a l sucker. The former i s about 0.34 mm. while the l a t t e r i s 0.12 mm. diameter. The complete cephalic spination. consists of 41 spines. These are arranged as a double alternating row of 33 spines on the rim and -4 on each lappet. The rim spines average 0.067 mm. being s l i g h t l y longer than the lappet spines which are 0.059 mm. The body c u t i c l e :is smooth, with s l i g h t s t r i a t i o n s but no scales l i k e Echinostomum sp. The narrow muscular pharynx i s not very prominent. It i s connected to the o r a l sucker by a short esophagus. The pharynx bifurcates just anterior to the acetabulum to form the two branches of the digestive t r a c t . The posterior l i m i t s of the branches were not apparent i n the specimens 58 examined. , The paired e l l i p t i c a l testes which l i e tandem i n posterior h a l f of the body, are approximately 0.31 x 6.17 mm. The club-shaped c i r r u s pouch i s situated just anterior to the acetabulum and to the r i g h t of the median l i n e . In some specimens, a long ( smooth muscular c i r r u s was observed projecting from i t . The seminal v e s i c l e i s not evident. The small globular ovary l i e s anterior to the l e f t of the anterior t e s t i s . The smaller oval Mehlis's gland l i e s median to i t . A seminal receptacle i s not apparent. The v i t e l l a r i a duct passes across the ventral side of the body between the ovary and the anterior t e s t i s . The v i t e l l a r i a glands are represented by prominent dark i r r e g u l a r l y globular masses l y i n g p a r a l l e l to the l a t e r a l borders of the body from the acetabulum to the posterior t i p . Near to the posterior, they merge across the dorsal part of the body. The extremely short l o o s e l y - c o i l e d uterus l i e s between the ovary and acetabulum. It passes to the l e f t of the acetabulum to open by the i n d i s t i n c t g e n i t a l pore at the l e f t of the midline. The non-operculate oval eggs are few, numbering from 9 to 22 i n the specimens examined. They are approximately 0.117 mm. long. The excretory ducts were not apparent i n these specimens. However, the slender, elongated, median excretory rese r v o i r extends from the posterior of the second t e s t i s and opens at the posterior t i p of the worm. 59 Infection In t h i s investigation i t was found that the d i s t r i b u t i o n of t h i s species was l i m i t e d to C - area. A t o t a l of 1393 worms were recovered from 13 infected muskrats As may be observed from Table 8, they were d i s t r i b u t e d throughout the entire digestive t r a c t . The greatest i n f e c t i o n occurred i i i the. small intestine where an average of 107.1 worms was co l l e c t e d . Discussion This description attempts to remove the c o n f l i c t i n distinguishing c h a r a c t e r i s t i c s outlined by Barker. In t h i s connection, i t i s believed that he described the species, Echinostomum callawayensis and Echinoparyphium oontiguum from a mixed series of specimens. This discrepancy was noted when c h a r a c t e r i s t i c s i n these trematodes f i t t e d both descriptions while others were not c l a r i f i e d by either description. Neveu-Lemaire indicates that t h i s genus can be separated from other genera i n the subfamily Echinostominae by the p o s i t i o n of the ventral sucker. In t h i s genus, Echinoparyphium, i t i s situated i n the anterior quarter of the body while i n the other genera, Echinostomum. Euparyphium and Hypoderaeum, i t i s situated close to the or a l sucker. Beaver separates Echinoparyphium from Echinostomum on the basis of the cephalic spination and the length of the 60 Ntnay 3NIJS31M H3WJOJS i n Uj 1 V 1-H3VI/VQ_iS < 10 61 uterus. On the basis of my study, i t i s recommended that these genera be separated upon the following c h a r a c t e r i s t i c s Echinoparyphium - 41 cephalic spines extremely short,, loosely c o i l e d uterus Echinostomum' - 37 cephalic spines long compactly c o i l e d uterus F l a g i o r c h i s proximus Barker Family Flaglorchidae Luhe 1901 Genus Plagiorchis Luhe 1899 Status This distome was also described o r g i n a l l y by Barker i n 1915, as a parasite of the muskrat. Since t h i s date, t h i s host has been reported infected by t h i s trematode i n Ontario, Ohio, Blichigan and Eastern Canada. The specimens from the muskrat i n B r i t i s h . Columbia were i d e n t i f i e d by the description of Barker. Infection Mature specimens of t h i s trematode occurred i n the small intestine of B.C. muskrats i n two r e a d i l y d i s -tinguished v a r i e t i e s , which w i l l be referred to ; as the • t y p i c a l ' and the ' a t y p i c a l ' . The former i s the described 'elongated oval-shaped' trematode. The l a t t e r i s a small oval trematode i n which the posterior h a l f of the body i s almost c y l i n d r i c a l while "the anterior h a l f i s f l a t t e n e d . Plate 71, F i g . 1 and 2. It was at f i r s t thought that these were separate species. However, detailed examination revealed no e s s e n t i a l distinguishing c h a r a c t e r i s t i c s between the two v a r i e t i e s , other than shape and s i z e . I t was also noted that the a t y p i c a l v a r i e t y always occurred i n the presence of the t y p i c a l v a r i e t y . The a t y p i c a l v a r i e t y occurred only i n muskrats from C - and D - areas. The greater number were c o l l e c t e d i n D - area, where a range of 10.6$ to 15.2$ a t y p i c a l specimens were co l l e c t e d . This variety was recorded only from.Springhouse i n C - area. AREA PLACE & DATE INF./TOTAL TOTAL •- INFECTION ATYPICAL NO. . SPECIMENS * C Springhouse, 1947 2/12 : 258 11 4.9$ D Radium, 1946 2/6 27 2 11.1$ Brisco, 1946 5/5 151 20 " 13.2$ Windermere, 1947 4/5 421 55 10.6$ Table 11. Infection by a t y p i c a l v a r i e t y of P. proximus. Discussion Additional evidence for wide l o c a l v a r i a t i o n i n i n f e c t i o n by a species of parasite i s noted i n the i n f e c t i o n by t h i s species i n C - area. This v a r i a t i o n i s i l l u s t r a t e d i n the following tabulation. The distance from Springhouse to Williams Lake i s about 12 miles, while that from Ochiltree to Williams Lake i s north-east about 17 miles. 63 PLACE & DATE INF./TOTAL INFECTION — — . . . CARCASSES. TOTAL AVERAGE $ INFECTED Williams Lake March, 1946 March, 1947 5/24 2/12 260 48 52 24 20.6% 16.6$ Ochiltree, 1946 . 3/14 32 10.6 21.4$ Springhou.se, 1947 9/12 238 26.4 75.0$ Mapes, 1947 1/2 . 38 -Table 12.' Comparison of i n f e c t i o n i n l o c a l i t i e s throughout C - area. It i s noted that for 1947, the i n t e n s i t y of the i n f e c t i o n doe's not vary greatly between •Williams Lake and Springhouse. The percent of muskrats infected however, i s 75$ at Springhouse and 16.6$ at 'Williams Lake. An opposite condition was i n ef f e c t i n 1946 for two adjoining l o c a l i t i e s . The percent infected v a r i a t i o n between Williams Lake and Ochiltree was only 20,8$ to 21.4$. The, average density, of. i n f e c t i o n at Williams Lake was 52 which outnumbered that of 10.6 worms recovered from muskrats at Ochiltree. The above table also i l l u s t r a t e s the range of i n f e c t i o n i n muskrats c o l l e c t e d i n successive years from the same l o c a l i t y . This range shown fo r Williams Lake was 20.8$ for 1946 with a decrease of 4.2$ to 16.6$ f o r 194?. Although the percentage of i n f e c t i o n did not vary greatly f o r the same period, the i n t e n s i t y of i n f e c t i o n varied widely. In 1946, the average i n f e c t i o n was 52 while f o r 1947, i t was 24. It i s thus noted that an o v e r - a l l decrease had taken place. 64 Quinqueserialis quinqueserialis (Barker and Laughlin 1911) Family Notocotylidae Luhe 1909 Subfamily Note-cotylinae Kossack 1911 Genus Quinqueserialis Herber 1942 Status The two species of Notocotylinae that i n f e c t the muskrat i n B r i t i s h Columbia are .r eadily distinguished .macroscopically from one another by the number of rows of protusible glands on the ventral surface. Q. quinqueserialis has f i v e rows while Notocotylus urbanensis has three rows. 0.. quinqueserialis -was f i r s t described by Barker > and Laughlin i n 1911 as Notocotylus quinqueserialis from specimens found in the cecum of the muskrat. In 1942, i n a description of the host-cycle, E.C. Herber l i s t e d i t as i n the genus Quinqueserialis. He separated this'genus from that of Notocotylus on the basis that the former has f i v e rows of ventral glands while the l a t t e r has only three rows. Like those genera of the subfamily Echinostominae, these are also frequent parasites of aquatic b i r d s and small rodents. It i s thus i l l u s t r a t e d further that the para-si t o l o g y of one vertabrate i s c l o s e l y r e l a t e d to that of another within the same habitat. Other records of Q. quinqueserialis as a parasite of the muskrat are outlined i n Table 1. Infection From Table 10, i t i s noted that t h i s species is, almost exclusively a parasite of the cecum. Even i n a high 65 i n f e c t i o n , i t was confined t o . t h i s region of the digestive t r a c t . In A- area, a n e g l i g i b l e number of specimens were collected from other segments of the i n t e s t i n e . In A-, C- and.E- areas, the percentage of i n f e c t i o n ranged from 40.5$ to 45.5$, while i n B- and D- areas, i t was 88.8$ and 93.0$ respectively. The i n t e n s i t y of i n f e c t i o n -was extremely variable. AREA PLACE INE./TOTAL .CARCASSES TOTAL INFECTION AVERAGE $ INF. Burnaby Lake 15/41 508 33.8 36.8 Lulu Island 11/24 490 44.5 45.8 A Sea Island 1/7 12 - 14.2 P i t t Meadows 4/4 567 141.7 100,0 Clayburn 4/4 700 175.0 100.0 B Duncan 8/9 615 76.8 86.6 Williams Lake 12/24(«46) 12/12('47) 922 1900 76.8 158.3 50.0 100.0 C Ochiltree Springhouse 1/14 0/12 164 — 7.1 Mapes 2/2 300 150.0 100.0 Brisco 5/5 173 34.6 100.0 D Radium 5/6 420 84.0 83.3 Windermere 5/5 740 148.0 100.0 Oliver 2/2 132 66.0 100.0 E M i l l Creek & Rutland 9/24 381 42.3 37.5 Kelowna 2/3 82 41.0 66.6 Princeton 1/1 850 - . -Table 13. D i s t r i b u t i o n of Q,. quinqueserialis i n each d i s t r i c t . 66 . "Table 13 i l l u s t r a t e s a considerable v a r i a t i o n within A - area. The Fraser River Valley ( P i t t Meadows and Clayburn) were 100$ p a r a s i t i s e d compared with a range of 14.2$ to 45.8$ among lower mainland muskrats.. Also, the former animals showed a higher i n t e n s i t y of i n f e c t i o n , 141.7 to 175. while the l a t t e r ranged from 33.8 to 44.5. Discussion The i n f e c t i o n on Sea Island was s l i g h t l y i r r e g u l a r to t h i s average. This may be explained by the f a c t that muskrats from Lulu Island examined at the same time were also not infected. It i s thus possible that i f carcasses' ', from Sea Island had been examined during January, they would have been infected to a s i m i l a r degree as those-from Lulu • Island. In C- area, Williams Lake was the o n l y l o c a l i t y with any measurable i n f e c t i o n . There was a" great difference i n the i n f e c t i o n at a s i m i l a r period between 1946 and 1947. In 1946, the average i n t e n s i t y was.76.8 i n a 50$ i n f e c t i o n , while f o r 1947, it was 158.3 i n 100$ i n f e c t i o n . Although only two carcasses from the Vanderhoof D i s t r i c t were examined, a high i n f e c t i o n was present. D - area i s int e r e s t i n g i n that the percentage i n f e c t i o n did not vary greatly. There was extensive v a r i a t i o n i n the i n t e n s i t y of i n f e c t i o n however, from the c e n t r a l l y located Radium. North t o B r i s c o ; a distance of 20 miles, i t was. only 34.6 while south to Windermere, also 20 miles, i t was 148. 67 E- area presented i r r e g u l a r i t i e s that are due to i n s u f f i c i e n t examinations from l o c a l i t i e s other than M i l l Creek and Rutland F l a t s . There was found however, a close r e l a t i o n between the average incidence i n muskrats from Kelowna and those from the M i l l Creek l o c a l i t y . Notocotylus urbanensis (Cort 1914) Family Notocotylidae Luhe 1909 Subfamily Notocotylinae Kossack 1911 Genus Notocotylus Diesing 1839 Status As mentioned previously, t h i s trematode i s r e a d i l y distinguished from Q,. quinqueserialis. The description of E.C. Harrah (1922) was used to i d e n t i f y specimens found i n the digestive t r a c t of several muskrats i n t h i s province. Of specimens described by Harrah, i t i s said, "Medium sized worms 2.5 mm. to 3.5 mm. long by 0.5 to 1.0 mm. wide, having three rows of ventral glands each row containing 13 to 14 glands". W.W. Cort (1914) described Ceoaria urbanensis. However, i t was Harrah who studied the mature adult worms and recently excysted immature specimens; compared the l a t t e r to Cort's description of the cecaria and concluded that one foreruns the other. Luttermoser (1935) confirmed the conclusion of Harrah, by experimental i n f e c t i o n with Cecaria urbanensis into domestic ducklings and a muskrat and recovered adult specimens of N. urbanensis from" the int e s t i n e . 68 Available l i t e r a t u r e shows that t h i s trematode has been reported from the Maryland muskrats. Other hosts include Aix sponsa (wood duck) and D a f i l a acuta ( p i n t a i l duck) from which A. Hassall collected specimens i n the intestine i n 1895. Infection N. urbanensis was the l e a s t abundant trematode coll e c t e d from the B r i t i s h Columbia muskrats. Previous reports indicate that i t i s primarily a parasite of the intestine and cecum.- I t was found.however, that i n this region the more common s i t e of i n f e c t i o n i s the colon. From the following tabulation, i t w i l l be noted that ,the average, colonic i n f e c t i o n i n A--, C-, and D- areas varied from 13.5 to 13.7 worms. The percent i n f e c t i o n however, was';16.25$ i n A- area, 34.5$ in C- area and 74.4$" in D- area. A smaller i n f e c t i o n occurred i n B- and E- areas. Negligible infections occurred in other segments of the digestive t r a c t . 69 AREA PLACE NO.INF./TOTAL INFECTION TOTAL AVERAGE % INF. Burnaby Lake 3/41 41 13.1 7.3 Lulu Island 6/24 74 12.3 25.0 A Sea Island 1/7 4 14.2 P i t t Meadows • 1/4 21 - 25.0 Clay burn 1/4 3 • - 25.0 B Duncan 2/9 5 2.5 22.2 Williams Lake : '46 10/24 206 20.6 41.6 n '47 9/12 92 10.2 75.0 U Springhouse 1/12 2 • - 9.3 Ochiltree 1/14 13 - 7.1 Mapes 2/2 10 5.0 100.0 Radium 4/6 126 31.5 66.6 D Brisco 3/5 12 4.0 60.0 Windermere 5/5 28 .5.6 100.0 M i l l Creek & Rutland 0/24 - — -E Kelowna 1/3 1 - -Oliver 0/2 - -Princeton 1/1 1 - -Table 14. Infection by N. urbanensis i n B.C. muskrats, 1944 - 1947. 1 70 Discussion The above tabulation shows that the l o c a l v a r i a t i o n i n percent i n f e c t i o n within an area i s not great. For instance, i n A-area, three f a i r l y separated l o c a l i t i e s registered 25$ i n f e c t i o n . S i m i l a r l y i n C-area, Springhouse and Ochiltree presented p a r a l l e l i n f e c t i o n s . NEMATODA C a p i l l a r i a ransomia Barker and Noyes 1915 ' Family Trichuridae R a i l l i e t 1915 Subfamily C a p i l l a r i i n a e R a i l l i e t 1915. . Genus C a p i l l a r i a Zeder 1800 Status ' , This i s the only nematode which was found i n f e c t i n g the muskrat to any extent.. Three specimens, of Trichuris„ opaca were c o l l e c t e d from one muskrat from Lulu Island. C a p i l l a r i a sp. are r e a d i l y distinguished from T r i c h a r i s sp; the former have a long slender.whip-like body while the l a t t e r has the stouter posterior h a l f d i s t i n c t l y separated from the slender anterior h a l f of the body. C a p i l l a r i a ransomia was another i n t e r n a l parasite of the muskrate i n Nebraska that was described by F.D. Barker i n 1915. The reported l i t e r a t u r e reveals that i t has been col l e c t e d from th i s host i n several areas, including eastern Canada, Michigan and Ohio. Infection _______ i Table 8 indicates a small incidence of i n f e c t i o n 71 from a l l areas of t h i s province. The main s i t e of i n f e c t i o n i s the small i n t e s t i n e . In A-area however, specimens were c o l l e c t e d from the stomach and cecum of two carcasses. In B-area, the nematodes were recovered from the cecum of the one muskrat^ so infected. Discussion E-area reported the highest, average intensity, of i n f e c t i o n as well as the highest percentage of i n f e c t i o n . The tabulation following i l l u s t r a t e s the d i s t r i b u t i o n of C a p i l l a r i a ransomia i n th i s area. I t i s noted also that the highest single i n f e c t i o n was c o l l e c t e d from a muskral^ i n thi s area. PLACE INE./TOTAL CARCASSES. INFECTION TOTAL AVERAGE RANGE Kelowna 1/3 28 Oliver 2/2 69 34.5 14-55 Princeton 0/1 - - -M i l l Creek & Rutland 11/24 . 47 4.2 1-11 Table 15. D i s t r i b u t i o n of C. ransomia i n E-area • CESTODA Hymenolepis sp. Family Hymenolepididae R a i l l i e t and Hanry 1909 Sunfamily Hymeholepidinae Ransom 1909 Genus Hymenolepis Weinland 1858 72 Status Only cestodes belonging to th i s genus were colle c t e d from the in t e s t i n e of the muskrat/. i n t h i s province. Hymenolepis evaginata, the t y p i c a l muskrat species was o r i g i n a l l y described by Barker and Andrews i n 1915 from the Nebraska muskrat. This parasite has been reported since as i n f e c t i n g t h i s host i n many widely scattered areas including Louisiana, Michigan, Ohio, eastern Canada and Great B r i t a i n , where i t was apparently introduced with i t s adult host. In B r i t i s h Columbia two species were evident; the t y p i c a l muskrat:species, H. evaginata and H. octocoronata, which normally infects Myocaster coypus (coypu or n u t r i a ) , a south american rodent. Thesespecies were i d e n t i f i e d ' e a s i l y , from R.C. Hughes, "Key to species of Hymenolepis". Infection Except f o r 3.75$ muskrats i n A-area infected by an average number of 3.7 worms i n the stomach, t h i s i s exclusively a parasite of the small i n t e s t i n e . Infection was only s l i g h t , ranging from 10.5$ i n C-area to 18.6$ i n D-area. S i m i l a r l y , the i n t e n s i t y of i n f e c t i o n was also s l i g h t , being an average range of 6 to 7.6 worms. In B-area, 55.5$ musk-rats were infected by an average of 2 cestodes. These enumerations are based on the number of scolices recovered. The method of s l i t t i n g the inte s t i n e f o r examination often divided a long cestode into several pieces. '73 TABLE 16. INTESTINAL INFECTION BY H. OCTOCORONATA LOCALITY i n INF./TOTAL INFECTION • . A-AREA CARCASSES. EXT. AVERAGE TOTAL' Infection by "large" v a r i e t y Burnaby Lake . 11/41 1-24 8.3 92 ' Lulu Island 11/24 1-26 7.7 85 Sea Island 1/7 12 - 12 P i t t Meadows 3/4 1-3 2 6 Clayburn 3/4 1-3 2 6 Infection by "small" v a r i e t y Burnaby Lake „ 3/41 60-many innum. Lulu Island 5/24 60-250* - 1000 Sea Island 6/7 40-250 t - 700 Pitt.Meadows 3/4 125-250* - 500 Clayburn 3/4 12-200* - 270 Muskrats infected by both v a r i e t i e s Burnaby Lake 2/41. Lulu Island 5/24 Sea Island 2/-7 P i t t Meadows 2/4 Clayburn 3/4 '  TABLE 17. INFECTION by B. EVACINATA i n C, D and E. AREAS AREA • LOCALITY NO. INF./TOTAL INFECTION CARCASSES EXTREMES. TOTAL c • Williams Lake . 1946 . NO CESTODES i 1947- 3/12 1-7 11 Ochiltree. NO CESTODES Sprin'gh^siS NO CESTODES Mapes 2/2 1 2 D Radium 2/6 1-16 . 17 Brisco NO CESTODES Windermere m - 1 E M i l l Creek • & Rutland 3/24 1-15 29 Kelowna NO CESTODES Oliver NO CESTODES • Princeton NO CESTODES 74 Also, due to the delicate nature of the anterior segments of these species, i n t a c t s c o l i c e s were sometimes d i f f i c u l t to' c o l l e c t . Microscopic examination of intact s c o l i c e s of a l.i'o'ni representative specimens revealed considerable yarie^ti-as within the two species- prevalent i n B.C. muskrats. In A-area, H. octocoronata occurred i n three d i s t i n c t v a r i e t i e s . Of these v a r i e t i e s , two possessed •7 I d e n t i c a l r o s t e l l a / armature, but were distinguished by si z e . In the "small" v a r i e t y , the intensity of i n f e c t i o n ranged from 60 to 250-*. In the "large" v a r i e t y , i t ranged from 1 to 26 i n d i v i d u a l s . These v a r i e t i e s both possessed ' a rostellum armed with elongated hooks i n a c i r c l e t of 8, which i s t y p i c a l for the species H. octocoronata, The t h i r d v a r i e t y , occurring within the "small" v a r i e t y , was disclosed by microscopic examination of intact s c o l i c e s . This aberrant type possessed a rostellum armed by -9 d i s s i m i l a r l y shaped hooks, compared to those of the. above v a r i e t i e s . Plate VIII, f i g . 1 and 2. However, the arrangement of the i n t e r n a l organs of the p r o g l o t t i d i s i d e n t i c a l ' t o t y p i c a l H. octocoronata specimens. According to R.C. Hughes (1941) there i s apparently no described species bearing nine r o s t e l l a r hooks. Literature since t h i s date also reveals no nine-hooked species. With the r o s t e l l a r armature as the only d i s t i n c t i v e character, these specimens are c l a s s i f i e d as an aberrant type of the species H. octocoronata. 75 Throughout C-, D- and E-areas, the t y p i c a l muskrat species,,H. evaginata, occurred. Infection was s l i g h t and scattered. In C-area ne g l i g i b l e incidence occurred at Williams Lake and Mapes during March, 1947. In D-area, Radium reported the higher i n f e c t i o n , where two. muskrats contained 17 cestodes. Incidence was also scattered and n e g l i g i b l e i n E-area. Table 17. l i s t s the degree of i n f e c t i o n i n the various l o c a l i t i e s surveyed. Description H. octocoronata (von Linstow 1879,) Euhrmann 1924 also Meggitt 1924. As mentioned previously, t h i s species occurred i n two v a r i e t i e s that are distinguished by the size of the s t r o b i l a . In the. "small" v a r i e t y they measured 30-50 u. x 315-330 u., while i n the "large" va r i e t y they were 120-160 u. x 680-720 u. The r o s t e l l a r armature of the pestle-shaped scolex consists of eight long, s l i g h t l y curved hooks. The average length of which i s 68u. The nine hooks of the "small" aberrant type are 45-47u. The four deep c i r c u l a r suckers -are 0.1mm. diameter. The three d i s c - l i k e testes, 0.058 mm. diameter, l i e i n a t r i a n g u l a r p o s i t i o n , one on the poral side and two on the aporal side. The slender club-shaped u n i l a t e r a l c i r r u s pouch extends about two-thirds across the width of the p r o g l o t t i d . The spinous c i r r u s i s approximately 0.027mm. long. 76 The median bilobed ovary l i e s near the posterior border of the p r o g l o t t i d , the eggs are 0.027 mm. Since t h i s i s the f i r s t record of this-species of Hymenolepis from _the...m'uskrat., t h i s b r i e f description seems pertinent. ^H. evaginata Barker and Andrews i n Barker 1915. Redescription of t h i s species i s unnecessary since a l l specimens c o l l e c t e d from the muskrat i n t h i s province are t y p i c a l for the species. However, a regional difference occurred i n the size of the r o s t e l l a r armature. Hughes (1941) indicated that the length of' the hooks are 7 u.' A l l B r i t i s h Columbia specimens, the length averaged 13 u. Their shape and proportions are the same. Discussion A£ Henry i n a review of the parj^ites and p a r a s i t i c diseases of the nutria indicates that H. octocoronata may be considered a normal parasite of this fur-bearing mammal. It i s indeed, int e r e s t i n g that the muskrat on the lower mainland of A-area. have acquired an introduced p a r a s i t e . The adapta-t i o n i s l o g i c a l , since both the described host and the acquired host are aquatic rodents of s i m i l a r ecology. I t i s . known that the nutria were introduced into the Fraser River v a l l e y and Lower Mainland not more than 10 years "ago by f u r -farming i n t e r e s t s . The extent of t h e i r natural d i s t r i b u t i o n i s not known, however. The presence of this species also i n Vancouver 77 Island muskrats and the f act that there i s evidence for.the presence of nutria i n t h i s region indicates that the a c q u i s i t i o n of H. octocoronata by the muskrat i n t h i s area i s separate from that on the mainland. Also no muskrat have been transplanted to Vancouver Island since the introduction from of nutria t-e- the Lower Mainland. The existence of a t y p i c a l v a r i e t i e s of cestodes has been reported i n several instances. It i s apparent that individual-physiology of the host i s not responsible since IE muskrats examined contained both the "large" and "small" v a r i e t i e s of H. octacoronata. The d i s t r i b u t i o n of the small 9-hooked v a r i e t y of this species i s however, l e s s constant than the normal 8-hooked v a r i e t i e s . Only two muskrats, from Lulu Island and Sea Island, were infected. The existence of t h i s type was concluded after a l l intact scolices from carcasses A48 and A62 were examine d. The d i s t r i b u t i o n - o f these two species of cestodes seems l o g i c a l l y explained by the presence of the natural b a r r i e r (Skagit Range of the Cascade Mountains) that separates the i n t e r i o r and coastal populations of muskrat and confines the nutira to the Fraser River v a l l e y . According to Henry, Sprehn observed an inflammation of the i n t e s t i n a l mucosa in instances of high i n f e c t i o n by H. octocoronata. In the muskrat no abnormal condition was evident, despite the f a c t that the incidence sometimes 78 attained 200+ cestodes i n a concentration of a 6 inch segment of the small i n t e s t i n e . The l i v e r of the muskrat i n t h i s province i s infected by two species-of l a r v a l cestodes: the s t r o b i l o -cercus.of Taenia taeniaformis and the p r o l i f e r a t i n g cysticercus of Cladotaenia sp. The l a t t e r species also occurred i n encapsulated cysts at the base of the mesentry. Since t h e ; f i r s t record by Linton i n 1884, Taenia  taeniaformis has been reported several times as a l a r v a l parasite of the muskrat (Table 1). It i n f e c t s the l i v e r of other rodents namely, Mus sp. and Microtus sp. The adult cestode t y p i c a l l y i n f e c t s F e l i s sp. Natural infections of Cladotaenia cooper! larva have been reported by, L.R. Penner (1938) from Microtus pine- torum scalopsoides and Peromyscus leucopus noveborascensis. The adult was recovered from A c c i p i t e r cooperi (Cooper's hawk). Experimental i n f e c t i o n of several small rodents including two young muskrats by eggs of Cladotaenia sp. from the goshawk produced t y p i c a l c y s t i c e r c i i n the l i v e r , pan-creas, kidneys and mesentries (Penner, unpublished reserach in Ameel, 1942). Following the description of two l a r v a l cestodes from the muskrat, D.J. Ameel (1942) states that consideration should be given to r a p t o r i a l birds as possible hosts f o r small hooked p r o l i f e r a t i n g c y s t i c e r c i . i 79 Infection Taenia taeniaformis was present only i n muskrats from Rutland i n E-area. In this i n f e c t i o n , 14 carcasses contained from 1 to 3 larvae, a t o t a l of 21 encysted singly on the periphrary of the l i v e r lobes. Compared to previous descriptions, these specimens were t y p i c a l for the species. Cladotaenia sp., i d e n t i f i e d by A. Mcintosh i n 1944, occurred i n muskrats at. Burnaby Lake and Lulu Island i n A-area. In A4, A6 and A75, t h i s larva was present i n cysts at the base of the mesentry. These cysts"varied i n s i z e from 10 to 30 mm. Several i n d i v i d u a l s c o l i c e s were co l l e c t e d from the duodenum of A2. I t i s possible that these s c o l i c e s were related tc the two cysts i n the l i v e r . The d e t a i l of the scolex was s i m i l a r to the l i v e r s c o l i c e s . PLACE SPEC. No. No. of CYSTS Burnaby Lake A2 2 A8 9 A12 1 A23 2 Lulu Island A46 10 A54 3 .A75 12 Table 18. D i s t r i b u t i o n of Cladotaenia sp. i n A-area. 80 Description Each l i v e r cyst of Cladotaenia sp. usually con-tained one bladder with several s c o l i c e s on i t , the general number being 8 to 12. A mesenteric cyst would contain numerous bladders with one to many s c o l i c e s on each. Por examination of the r o s t e l l a r armature, a scolex was crushed between a microscopic s l i d e and cover-slip i n a g l y c e r o l mount. In those specimens examined, there were from 42 to 48 small hooks arranged i n a double row (Plate VI, f i g . 2 ) . The r o s t e l l a r hooks from c y s t i c e r c i i n the mesenteric cyst of A75 were poorly defined, but i t i s assumed from their number that they are the same species as the other cysts. Discussion The i n f e c t i o n b y , l a r v a l cestodes of the muskrat i n B r i t i s h Columbia i s s l i g h t . This incidence i s apparently not detrimental to the health of the host, as a l l carcasses so infected were i n a normal condition. As previously discussed i t i s noted that both species are t y p i c a l l y l a r v a l parasites of small rodents while the adult occurs i n t y p i c a l predators of these mammals. -Thus further evidence i s given to the hypothesis that para-s i t i s m i s related to the ecological associations of animals. The Cladotaenia sp. present i n the carcasses examined somewhat resembles the f i r s t species of l a r v a l cestode described by D.J. Ameel. However, since he does not 81 i d e n t i f y i t , this resemblance i s based on h i s description and i l l u s t r a t i o n of cysts. The shape of the hooks i s quite d i f f e r e n t . .With this i n mind, the B r i t i s h Columbia species may be a c l o s e l y r e l a t e d species. ACANTHO CEPHALA Except f o r an acanthocephalan, a l l genera of i n t e r n a l parasites of the muskrat found i n t h i s survey have been previously recorded from t h i s host. Seven specimens of a species belonging to t h i s group of parasites were recovered from four muskrats i n C-area. Six of these came from three rSarcasses at Ochiltree i n 1946, while one was c o l l e c t e d from a muskrat at Springhouse i n 1947. Using the key of H.J". Van Cleave (1923), d i s t i n -guishing characters indicate that these specimens belong to the family Corynosomidae and r e l a t e d to the genus Pplymorphus Ltthe 1911. Sp-ecies i n t h i s genus are p a r a s i t i c i n aquatic b i r d s . A recent p u b l i c a t i o n of Helen L. Ward which redes-crib es the species Polymorphus obtusus Van Cleave, 1918 indicates that the species from the muskrat i s r e l a t e d to i t . Description The specimens examined measured 2 to 2.4 mm. long and 1.0 mm. wide. The c y l i n d e r i c a l club-shaped protusible proboscis i s covered with 9 or 10 p a r a l l e l a l t e r n a t i n g rows of uniformly sized spines,-45 u. long. It f i t s into an elongated proboscis receptacle that extends to the body c o n s t r i c t i o n . The two 82 elongated sac-like lemnisci l i e p o s t e r i o r l y ( f r o m t h i s receptacle. The anterior t h i r d of the body i s wider than the posterior. From the c o n s t r i c t i o n i t extends cloak-like' around the base of the proboscis. The external surface of t h i s region i s covered by innumerable rows of minute spines that decrease In size toward the c o n s t r i c t i o n . The posterior two-thirds of the body i s non-echinate. The posterior t i p of the body also extends from a c o n s t r i c t i o n and is of considerably smaller diameter. In the male, i t i s s l i g h t l y f l a r e d to form a bursa-like t i p . In the female, i t is rounded toward the g e n i t a l aperture. In the male, the two elongated testes l i e together at about the middle of the body. They measure 1.56 mm. long and 0.088 mm. wide. Posterior to them i s a voluminous enlargement that represents the cement receptacle. This i s connected to the g e n i t a l opening by ducts. The cement glands are between the receptacle and the testes. In the female, the body cavi t y i s f i l l e d with numerous ovarian masses. The short funnel-shaped uterine duct extends from the posterior c o n s t r i c t i o n to the t i p of the body. The females examined contained no mature ova on which dimensions could be taken. Discussion When these specimens are compared with H.L. Ward's description notable differences are evident. • But the 83 following s i m i l a r i t i e s indicate that the species are r e l a t e d ; the spinous anterior region of the body; the presence of anterior and posterior constrictions of the body; the shape of the cement receptacle i s s i m i l a r and the copulatory bursa are s i m i l a r l y shaped. The d i f -ferences l i e i n the shape of the testes, which are oval i n her description and the proboscis. These differences are d e f i n i t e l y s i g n i f i c a n t and further research i s necessary before concluding the exact r e l a t i o n of t h i s species to other species of Polymorphus. Present knowledge indicates that acanthocephalan parasites are r e l a t i v e l y unimportant. The i n f e c t i o n from the muskrat i s apparently i n s i g n i f i c a n t . I t i s possible that t h i s i s an a c c i d e n t a l host, since Van Cleave indicates that t h i s genus i s p a r a s i t i c i n b i r d s . 84 RESULTS of THIS INVESTIGATION This survey revealed that 74.0$ of the muskrats examined contained more than 5 specimens of i n t e r n a l para s i t e s . Since a l l the carcasses were apparently i n good condition at death, t h i s percentage may be accounted as normal parasitism. . AREA • LOCALITY TOTAL TOTAL EXAMINATIONS INFECTED INFECTED A Burnaby Lake 41 31 75.6 Lulu Island 24 20 80.0 Sea Island 7 5 55.5 P i t t Meadows 4 4 100. Clayburn 4 4 100. . B Duncan 9 7 77.7 C • Williams Lake, 1946 24 17 70.8 1947 12 12 100. Ochiltree 14 2 11.1 Springhouse 12 8 66.6 Mapes 2 2 100. D Radium 6 5 83.3 Brisco 5 5 100. Windermere . 5 . 5 ' 100. E M i l l Creek & Rutland 24 . 15 62.5 Kelowna 6 - 2# 2 50.0 Oliver 2 2 100. Princeton 1 1 -TOTAL 202' ' 148 74.0 Table 19. Degree of Normal Parasitism i n the Muskrat i n B r i t i s h Columbia. #2 carcasses discarded as too decomposed f o r examination. 85 It i s suggested that for further study i n t h i s f i e l d , a basic number of 12 specimens be u t i l i z e d , i f comparison studies are to be completed. Reports from A-area indicate that the 1946 catch was the smallest since 1945 when a peak was reached. One trapper attributed the 1945 peak to overtrapping due to high prices at that time. Examination of a graph of the royalty paid on muskrat p e l t s w i l l reveal that t h i s peak was one of normal occurrence. v If the actual returns for the 1946 season are a minimum for t h i s cycle, i t may be i n t e r e s t i n g to note the r e l a t i o n of the pulmonary i n f e c t i o n to low population densities. At present i n s u f f i c i e n t evidence prevents further discussion of t h i s r e l a t i o n i n " B r i t i s h Columbia. However,' as indicated previously, Warwick noted a r e l a t i o n but hesitated to define i t . It i s concluded that m o r t a l i t y as a r e s u l t of excess parasitism i s probably n e g l i g i b l e i n the muskrat i n t h i s province. The mortality as a re s u l t of disease cannot be determined at t h i s time due to i n s u f f i c i e n t evidence. 86 SIGNIFICANCE of DISEASE and PARASITISM ' .in.BRITISH COLUMBIA. MUSKRATS*  As indicated above, only normal parasitism was encountered i n t h i s survey. I t i s apparent that other pre-disposing factors must be present before any abnormal con-d i t i o n associated with the parasitism w i l l manifest i t s e l f . In such instances, the parasitism would be the secondary cause of the diseased condition. It has been shown i n Table 8 that a d e f i n i t e d i s t r i b u t i o n exists f o r the d i f f e r e n t parasites of the muskrat. From t h i s table, i t i s noted that Echinostomum  coalitum and Hymenolepis octocoronata are dominant i n A-area, whereas Echinoparyphium contiguum infects t h i s host only i n C-area. The greatest i n f e c t i o n by P/lagiorchis proximus occurred i n D-area while C a p i l l a r i a ransomia infected more muskrat i n E-area. There i s thus a constant incidence v a r i a t i o n of parasites throughout B.C. It has also been observed that d e f i n i t e l o c a l variations, i n incidence and percentage of i n f e c t i o n occur. It i s d i f f i c u l t to attribute such variations to climate due to the r e l a t i v e l y short distance i n which they occur. Other factors that may contribute to t h i s v a r i a t i o n are water, p o t e n t i a l and type of food and population densities. The condition of the water has been shown to be an important factor i n the dissemination of parasites and e s p e c i a l l y disease. The.stagnant nature of water i n fe 87 drainage ditches would f a c i l i t a t e higher i n f e c t i o n than the. usually faster-moving waters of creeks, and ponds. Abundant evidence shows *that c e r t a i n diseases are disseminated through water. For instance, the. preva-lence of tularemia among muskrat i n Alberta. The organism, once introduced onjbo an area p r e v a i l s u n t i l the enti r e population i s k i l l e d (Parker to Brown, 1944). Apparently the causative organism i n the pulmonary i n f e c t i o n studied by Vifarwick was spread through water. . He found the diseased animals 16 miles apart. As f o r parasites, many cestodes and nematodes and a l l trematodes require water i n order to propagate. The type of food present i s the second f a c t o r that contributes to the d i f f e r e n t degrees of i n f e c t i o n by diseases and parasites between two l o c a l populations. Food po t e n t i a l i s a l i m i t i n g factor for the s u r v i v a l and increase of a population. Abundant desirable vegetation prevents overcrowding on the feeding areas, thus decreasing the chance of contact between healthy and diseased animals. . In connection with d i e t and parasites, a predominance of coarse fibrous grass-like vegetation i n the digestive t r a c t of muskrats from the M i l l Creek and Rutland l o c a l i t y was noted. This was i n contrast to the usual stomach and cecal content of f i n e l y divided yellow or green vegetation. S l i g h t parasitism was associated with t h i s fibrous diet . 88 Regarding the basis for a comparison between the age of a muskrat and the intensity of a p a r a s i t i c i n f e c t i o n , i t was noted that i n those carcasses on which age determination was possible, no r e l a t i o n e x i s t s . A juvenile animal was apparently p a r a s i t i s e d to a degree si m i l a r to that of an adult trapped at the same time. Parasitism i n those k i t s examined was n i l . This complete absence of parasites should not be accepted as a normality, since only s i x carcasses were examined throughout a period of 10 days from one l o c a l i t y (Burnaby Lake, A-area). I t may be also noted that an adult examined during the same period was free of parasites. 89 C O N C L U S I O N S This investigation' revealed that the muskrat trapped i n B r i t i s h Columbia i s not greatly affected by disease and parasites. Analysis of reports from game-wardens and trappers indicate that t h i s important f u r -bearer i s apparently more affected by wounds due to i n t r a -s p e c i f i c s t r i f e than by actual diseases. These wounds which are most dominant during the spring sexual f i g h t i n g reduce the value of p e l t s c o l l e c t e d at t h i s time. In some l o c a l i t i e s , p a r t i c u l a r l y , the.Lower Mainland, where trapping i s c arried out within municipal boundaries, and several trappers c o l l e c t on the same t e r r i t o r y , considerable maim-ing of muskrats results when an animal escapes from a trap. This i s more evident where traps are not "drown set". Pathological conditions include two pulmonary conditions, and a tumorous condition.^ . ' . With regard to parasitism, although 74.0$ of the carcasses were infected, the i n f e c t i o n i n each carcass was not s u f f i c i e n t to produce any pathological condition. With the exception of one, a l l species of parasites recovered from the muskrat i n t h i s province have been previously recorded. T h i s ' l i s t includes: trematodes, Echinostomum coalitum. Echinoparyphium continuum. Quinqueserialis quinqueserialis, Notocotylus urbanensis and Plagiorchis proximus; adult cestodes, Hymenolepis evaginata and Hymenolepis octocoronata; l a r v a l cestodes, Taenia 90 taeniaformis and Cladotaenia sp.;. nematodes, C a p i l l a r i a  ransomia and a few T r i c h u r i s opaca. The new record i s an Acanthocephala, r e l a t e d to Polymorphus (Family Corynosomidae) From analysis of the information c o l l e c t e d i n t h i s study, the following conclusions are derived: 1) I t i s apparent that the parasites which in f e c t the muskrat i n B r i t i s h Columbia are or have become normal to t h i s host. 2) There i s a d e f i n i t e regional prevalence fo r two species of these parasites. Hymenolepis octocoronata i s found only i n A-area (Lower Mainland and Fraser River v a l l e y ) , and B-area (Vancouver Island/)' while Echinoparyphium continuum i s l i m i t e d to C-area (central B.C.). 3) There are cer t a i n l o c a l differences i n the i n t e n s i t y and incidence of i n f e c t i o n by • the d i f f e r e n t species of parasites. These differences are not at t r i b u t e d to climate but.to different water and food conditions. 4) There i s no apparent difference, due to age, i n the degree of parasitism between adult and juvenile muskrats. M o r t a l i t y , as a r e s u l t of excess parasitism, i s probably n e g l i g i b l e i n the muskrat i n B r i t i s h Golumbia. 92 ILLUS TRATIOHS Plate V Echinostomum caLlawayensis. Ventral view. Drawn, at. X150, with camera l u c i d a . Uote: s h e l l gland = Mehlis 1 gland. Plate VI P i g . 1 Oral sucker and cephalic spination of E, callaway-ensis. Drawn, at X250, with camera l u c i d a . P i g . 2 R o s t e l l a r hook of the cestode,^Cladotaenia sp. Drawn, at X300, with camera l u c i d a * Plate VII Plagiorchis proxi,mus. P i g . 1 A t y p i c a l specimen, as determined from the descrip-t i o n of F.D. Barker F i g . 2 A specimen of the ^aberrant type' that i s present i n the muskrat i n B r i t i s h Columbia. Both figures are drawn, at X150, with camera l u c i d a . Plate VIII F i g . 1 R o s t e l l a r hook of the 'large 1 and 'small' v a r i e t i e s °^ Hymenolepis octocoronata. Scale. 10 mm./ 25.1 u. F i g . 2 Rostellar hook of the 'small aberrant* v a r i e t y of H. octocoronata. Scale, 10 mm. = 25.1 u. F i g . 3 Ro s t e l l a r hook of Hymenolepis evaginata. Scale, 10 mm. = 3.7 u. Above figures drawn with camera l u c i d a . F i g . 1 & 2 at X 300. F i g . 3 at X900. ^ F i g . 4 Immature proglot t i d s of H. octocoronata. A composite drawing, the outline of which was completed with 93 camera lucida, at X150. Plate IX A possible new species of Ac antho c ephala. Pig, 1 Composite drawing showing i n t e r n a l organs of male. Outline drawn by camera lucida" ~at XI50. P i g . 2 D e t a i l of the hooked proboscis-. Drawm, at XSOO, with camera l u c i d a . v. Pi g , 3 D e t a i l of the i n d i v i d u a l hooks of proboscis. Drawm with camera lucida, at X300. Scale, 10 mm. = .13 u.. Plate X A possible new species of Acanthocephala. Composite Brawing of the i n t e r n a l organs of a female. Outline drawn with camera lucida, at XI50. •LtPttAUC •ORAL 5UCKfR PHARYNX L~lRRU5 L/RRU5POUCt1 ACETABULUM UTERUS •5MELL CLAW •DMRY wi—YOLK DUCT m B J V/TELIAR/A TESTES EXCRETORY RE5ERVOIR PLATE: V 9 7 Fi<j. 4> PLbTE V/// 98 A/ECK RETRACTOR *• PROBOSCIS RECEPTACLE PR0B0SCI5 RECEPTACLE Le MNISCUS •BRAIN ANTERIOR CONSTRICTION RE TINACUL A SUSPENSORY LIGAMENT TESTES CEMENT GLANOS CENTRAL LIGAMENT CEMENT RECEPTACLE" • POSTERIOR CONSTRICTION -COPULATORY BURSA Fi Ficj. 2 PLATE IX i 100 R E F E R E N C E S ALLEN, J.A. 1934 Parasites of Pur-bearing Animals. 5th P a c i f i c S c i . Congr. Can. Proc. 1933 5: 2981-9. AMEEL, D.J. . 1932 The Muskrat, a New Host f o r Paragonimus. S c i . N.S. 75 (1945): 382. 1942 Two Larval Cestodes from the Muskrat. Trans. Amer.Micr. Soc. 61 (3): 267-271.1PP1. BAPJQSR, E.D. . 1915 Parasites of the American Muskrat. (Fiber  zibethleus). J . P a r a s i t o l . 1 (4): 184-197. 1916 A New Monostome Trematode Parasite i n the Muskrat, with a Key to the Parasites of the American Muskrat. Trans. Amer. Micr. Soc. 35 (3): 175-184. BAYLISS, H.A. ; ' ' 1.935 Some P a r a s i t i c Worms from the Muskrats i n . Great B r i t a i n ; " Ann. Mag. Nat. H i s t . London 15 (10): 543-549. BEAVER, P.O. 1937 Experimental Studies on Echinostoma revolutum (Froeli c h ) , a Fluke from Birds and Mammals. 111..Biol. Mongr. 15 (1): 1-96. BROWN, J.H. 1944 The S u s c e p t i b i l i t y of 'Fur-bearing Animals and Game Birds to Tularemia. Can. F i e l d N a t u r a l i s t 58 (2): 55-60. BRYD, E.E. and REIBER, R.J. 1942 Three Flukes from Small Mammals. J.« Tenn. Acad. S c i . 17 (1): 143-156; 101 CiH^U^LER, Asa G, 1941 Helminths of Muskrats In South-east Texas. J. P a r a s i t o l . 27 (2): 175-181. CORT, W.W. 1914 Larval Trematodes from North American Fresh-water S n a i l s . - . J. P a r a s i t o l . 1 (2): 65-84. COWiSN, I. MoT. 1939 Vertebrate Fauna of the Peace River D i s t r i c t of B r i t i s h Columbia. Occasional Papers of B.C. Prov.Mus.. No. 1: 1-102. DOZIER, H.L. 1943 Occurrence of Ringworm Disease and Lumpy Jaw i n the Muskrat i n Maryland. J . Amer. Vet. Med. Assoc. 102 (795): 451-453. ERRINGTON, P.L. 1946 Special Report on Muskrat Disease. Excerpted from the Quarterly Report, July to September, 1946. Iowa Cooperative W i l d l i f e Research Unit. HARRAH, E.C. 1922 North American Monostomes P r i m a r i l y from Freshwater Hosts. • 111. B i o l . Mongr., Urbana. 7: 1-106. HENRY, A. 1931 Les Parasites et les Maladies P a r a s i t a i r e due Ragondin. B u l l . Soc. Nat. Acclimat. France. 78 (12): 421-447. HENSLEY, A.L. and TWINING, H. 1946 Some Early Summer Observations on Muskrats i n North-eastern C a l i f o r n i a Marshes. C a l i f . F i s h & Game 32 (4): 171-181. ' 102 HERBER, E.C. 1942 L i f e History Studies of Two Trematodes. of the Subfamily Notocotylinae. J. P a r a s i t o l . 28 (3): 179-184. HOLLISTER, N. 1911 A Systemic Synopsis of the Muskrats. North American Fauna, No. 32. HUGHES, R.C. 1940 The Genus Hymenolepis Weinland 1858. Tech. B u l l . Okla. Agric. Exp. Sta. 8; 1-42. 1941 A Key to the Species of Tapeworms i n Hymenolepis. Trans. Amer. Micr. Soc. 60 (3): 378-414. KUNTZ,' R.E. 1943 Cysticercus of Taenia taeniaformis with .. Two Strob i l a e . J. P a r a s i t o l . 29 (6): 424-25. LAW, R.G. and KENNEDY, A.H.' . . 1932 "Parasites of Fur-bearing Animals". Dept. of Game & F i s h e r i e s , Ont. B u l l . No. 4: 1-30. LEIGH, W.H. 1940 Preliminary Studies oh Parasites of Upland Game Birds and Fur-bearing Mammals i n . . I l l i n o i s . " B u l l . I I I . Nat. H i s t . Surv. 21 (5): 185-194. LLOYD, H. 1925 Introduction of the Muskrat and Rocky Mountain Goat on Vancouver Island. Can. F i e l d N a t u r a l i s t . 39: 151-52. LUTTERM0SER, G.W. 1935 A Note on the L i f e History of the Monostome, Notocotylus urbanensis. J. P a r a s i t o l . 21 (6): 456. MacF-s-'J.^HE, , R . 103 MacFARLANE, R. 1905 Notes on the Mammals Collected and Observed i n the Northern Mackenzie River District., with Remarks on Explorers and Explorations of the Far North. Proc. U.S. Nat. Mus. 28: 737. MCINTOSH, A. 1940 Cladotaenia f o x i n.sp. i n falcon, F a l c i  peregrinus. North America. Proc. Helminthol. S o c , Washington, 7: 71-73. MEGGITT, F.J. 1924 Cestodes of Mammals. iv4282 pp. London. MUNRO, J.A. and COWAN, I.. MoT. 1944 Preliminary Reports on the Birds and Mammals of Kootfenay National Park, B r i t i s h Columbia. Can. F i e l d N a t u r a l i s t 58 (2): 34-51. MUNRO, J.A. NEVEU-LEMAIRE, M. 1936 T r a i t e d»Helminthologie. Medicale et Vetinaire. xxi4l-1514 pp. avec 787 f i g . Vigot Freres, editeurs. OLIVIER, L. 1947 Observations of Birds and Mammals•in Central B r i t i s h Columbia. Occas. Papers, B.C. Prov. Mus. No. 6, 1-165. 1938 A New Trematode (Allassogonoporus margihalis from the Muskrat. J . P a r a s i t o l . 24 (2): 155-160. OLSEN, O.W. 1939 Schizotaeniasis i n Muskrats. J . P a r a s i t o l . 25 (3): 279. PENN, G.H • > 1942 P a r a s i t o l o g i c a l Survey of Louisiana Muskrats. J. P a r a s i t o l . 28 (4): 348-349.' 104 PENN, G.H. ,'Jr., and MARTIN, E.C. 1941 The Occurrence of Porocephaliasis i n Louisiana Muskrats. J. W i l d l i f e Management 5 (1): 13-14. FENNER, L.R. 1938 A Hawk Tapeworm which produces P r o l i f e r a t i n g Cysticercus i n Mice. Abst. suppl. J . P a r a s i t o l . 24: 25 1938 Schistosomatium from the Muskrat, O.zibethica i n Minnesota and Michigan. J . P a r a s i t o l . 24 (6): suppl. 42 pp. 1941 The Status of Urotrema s h i l l i n g e r i P r i c e PRICE, E.W. 1931 (Trematoda: Urotrematidae). Trans. Amer. Micr. Soc. 60 (3): 359-364. 1931 Four New Species of Trematode.Worms from the Muskrat (0. zibethica) with a Key to Trematode Parasites of the Muskrat. Proc. U.S. Nat. Mus. 79 (4): 1-131. PRITCHARD, A.L. 1934 Was the Introduction of the Muskrat i n the Queen Charlotte Islands Unwise? Can. F i e l d N a t u r a l i s t , 48: 103. RAUSCH, Robert, L.. 1946 Parasites of the Ohio Muskrats. J. W i l d l i f e Management 10 (1): 70 RUSH, W.M. 1927 Notes on the Diseases of Wild Game Mammals. J". Mammalogy 8 (2): 163-65. SETON, E.T. 1909 L i f e H i s t o r i e s of Northern Animals. Vol. 1. C. Scribner's Sons, New York, 1220 pp. SHILLINGER, J.E. 1933 The Significance of W i l d l i f e Disease. Proc. 5th Pac. S c i . Congr. 4: 2977-81. 105 SMITH, F.R. 1938 Muskrat Investigations i n Dorchester County, Maryland, 1930-34. C i r c . U.S< Dept., Agr. No. 474, 1324 pp. STORER, Tracy I. 1938 The Muskrat, as Native and A l i e n ; a Chapter i n the History of Animal Acclimatization. Calif...Fish and Game 24 (2) : 159-175. SVIHLA, A. and SVLHLA, R.D. 1931 The Louisiana Muskrat. J. Mammalogy 12 (1): 12-28. SWALES, W.E. 1933 A Review of Canadian Helminthology. I. The present status of knowledge of the helminth parasites' o f domesticated and semi-domestica-ted mammals and economically important birds i n Canada, as determined from work published p r i o r to 1933. Can. J. Res. 8: 468-477. II . Additions to Part I, as determined from a study of p a r a s i t i c helminths c o l l e c t e d i n Cana da. Can. J . Res. 8: 478-481. SWARTH, H.S. 1922 Birds and Mammals of the St i k i n e River Region of Northern B r i t i s h Columbia and South-eastern Alaska. Univ. C a l i f . Publ. Zool. 24 (2): 125-314, plate 8, 34 f i g . i n text. 1924 Birds and Mammals of the Skeena River Region of Northern B r i t i s h Columbia. Univ. C a l i f . Publ. Zool. 24 (3): 315-344. plate 9-11, 1 f i g . i n text. TRAVIS, B.V. 1939 Descriptions of Five New Species of F l a g e l l a t e Protozoa of the Genus Giardia. J . P a r a s i t o l . 25 (1): 11-17. 106 "VAN CLEAVE, H.J. 1923 A Key to the Genera of Acanthocephala. « Trans. Amer. Micr. Soc. 42 (4): 184-191. WALLACE, F.G. and PENNER, L.R. 1939 A New L i v e r Fluke of the Genus Opistorchis. J . P a r a s i t o l . 25 (5): 437-440. WARD, Helen, L. 1943 A Redescription of Polymorphus obtusus Van Cleave, 1918. (Acanthocephala). J. P a r a s i t o l . 29 (4): 289-291. WARWICK, T. 1937 The Occurrence of Disease among Muskrats (0. z i b e t h i c a ) . i n Great B r i t a i n during 1954. J . Animal E c o l . 6 (1): 112-114. WEBSTER, J.D. 1947 Studies on the Genus Hymenolepis with description of Three New Species. J. P a r a s i t o l . 53 (2): 99-106. W00DHEAD, A.E. 1930 The Diseases of the Muskrat. Amer. Fur Breeder 3 (1): 30. 107 A B S T R A C T From 750 "outline questionaire" pamphlets mailed h to registered trappers i n B r i t i s h Columbia, 133 or 17.7$ were returned. Of these, 9.7$ trapped muskrat on t h e i r t e r r i t o r y and 8.0$ reported no muskrats. Through the cooperation of game-wardens and trappers 20£ muskrat carcasses were sent during trapping season from 17 d i f f e r e n t l o c a l i t i e s to the University of B r i t i s h Columbia f o r examination f o r diseases and parasites from October 1944 to May 1947. This survey revealed that 74.0$ of the carcasses were p a r a s i t i s e d by 12 species of i n t e r n a l parasites. These included: trematodes; Echinostomum coalitum, Echinoparyphium contiguum, Quinqueserialis quinqueserialis, Notocotylus urbanensis and Plagiorchis proximus;. adult cestodes, Hymenolepis octocoronata and Hymenolepis evaginata; nematodes, C a p i l l a r i a ransomia and a few T r i c h u r i s opaca and a new record of i n f e c t i o n for t h i s host, an Acantho-cephala, related to the genus Polymorphus (Coryhosomidae). Two l a r v a l cestodes were found i n f e c t i n g the l i v e r ; the strobilocercus, Taenia taeniaformis and a p r o l i f e r a t i n g cysticercus, Cladotaenia sp. Pathological conditions a f f e c t i n g the muskrat include two di f f e r e n t pulmonary conditions and a tumorous condition. There was also frequent i n f e c t i o n of wounds. 108 It was concluded that: 1) The parasitism i n B r i t i s h Columbia muskrats i s normal. 2) There i s considerable regional difference i n the prevalence and abundance of these normal parasites. 3) There i s no apparent difference, due to age, i n the parasitism of adult and juvenile muskrats. 4) The mortality, as a r e s u l t of excess, p a r a s i -tism, is probably n e g l i g i b l e . Also included i n this i n v e s t i g a t i o n - i s a complete h i s t o r i c a l review of the parasites of the muskrat and a d i s t r i b u t i o n a l survey of this,fur-bearer. 

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