Topical anesthesia mitigates the pain of castration in beef calves

Castration involves the removal of the testes, and is performed to improve product quality and management of male calves. The procedure has been proven to cause significant pain and stress, and despite several attempts to reduce the impact of castration on animal welfare, there has yet to be a practical and affordable option made available for farmer application. In order to address this issue, we conducted 2 trials (n = 18 and 27) to examine the efficacy of topical anesthetic Tri-Solfen (TA) to alleviate the pain of surgical castration. Angus bull calves (135.8 ± 5.7 kg) aged 3 to 4 months were randomly allocated to 3 treatment groups, including surgical castration, castration in combination with TA, or un-castrated controls. In Trial 1, pain-related behavior was assessed using a customized numerical rating scale (NRS) over 4 h. In Trial 2, pre- and post-operative skin sensitivity of the wound and peri wound areas was assessed using an electronic von Frey anesthesiometer (IITC Life Sciences, Woodland Hills, CA, USA) and von Frey monofilaments (300g). Sampling was repeated at 1 min and 2, 4, 6 and 24 h after castration. Pain threshold was measured as maximum pressure (g) exerted by the electronic anesthesiometer to invoke animal reflex, and responses to the von Frey monofilaments were scored from 0 to 3 using a NRS, based on local and central motor reflexes. Calves treated with TA displayed significantly less pain-related behaviors up to 3.5 h after castration than untreated calves (P < 0.001) and did not differ from un-castrated controls. Topical anesthetic-treated calves also exhibited significantly greater pain threshold of the wound (559.2 ± 14.3 g) and surrounding skin (602.8 ± 16.5 g) than untreated calves (446.0 ± 18.9 g and 515.3 ± 20.4 g respectively; P < 0.001). Control and TA-treated calves had significantly lower mean response scores to von Frey stimulation than untreated calves (0.333, 0.978 and 4.289 respectively; P < 0.001). Results indicate that TA effects rapid and prolonged pain alleviation in calves up to 24 h after castration. Topical anesthesia may present a cost-effective, practical on-farm approach to pain alleviation and is proposed as a potential tool for reducing the welfare impact on the beef animal of routine husbandry procedures. The study is from the Faculty of Veterinary Science, University of Sydney, Camden NSW, Australia.

Lomax S, Windsor PA. J Anim Sci 2013 Aug 21 [Epub ahead of print].

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