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Assessment of lasting pain following castration in 2-week-old calves

Yoo, Seonpil

Few methods are available to assess pain during healing and none are specific for pain following castration in calves. This study aimed to assess changes in lying behavior and memory as indicators of pain in the days and weeks after castration. Based on previous studies, we predicted that an increase in the number of short-duration lying bouts and incomplete lying bouts (bending front legs but hindquarters remain elevated) can serve as an indicator of evoked pain (i.e., associated with pressure on the wound), and that deficits in reference memory can serve as an indicator of cognitive load associated with lasting pain. Forty 14-day-old male calves (24 Holstein; 16 Holstein x Angus crossbred) were pseudo-randomly assigned to 1 of 4 treatments based upon a 2 x 2 factorial design, considering castration method (band vs. surgical castration), with or without supplementary week-long meloxicam treatment. At castration, all calves were provided multimodal analgesia, including sedation, a local block, and ketoprofen; calves in meloxicam treatment received additional pain medication (meloxicam) every other day during the 1st and 4th weeks following castration, when previous research suggests they experience the most pain. Lying behavior was recorded using accelerometers from 4- to 42-day of age. Calf memory was tested daily using a modified hole-board test in weeks 1 and 4. The day after castration calves in all 4 treatments engaged in more short-duration lying bouts compared to castration day (3.50 ± 0.54 vs. 6.38 ± 0.54), suggesting that the multimodal analgesia provided was insufficient to fully alleviate pain on the day after castration. Band-castrated calves exhibited a greater number of short-duration lying bouts on the day following castration compared to surgically castrated calves (7.64 ± 0.79 vs. 5.13 ± 0.74) indicative of more pain in band-castrated calves at this time. We found limited effects of castration method or additional meloxicam administration on behaviors during the 4th week after castration. We found no effect of castration method or supplemental NSAID on measures of calf memory. Our work provides the first evidence that an increased number of short lying bouts can serve as an indicator of pain in calves during the first days after castration.

Dataset

University of British Columbia Library

10.14288/1.0448028

https://doi.org/10.5683/SP3/9Y2CYQ

Dataverse