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. 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 mo were randomly allocated to 3 treatment groups, including surgical
castration,
castration in combination with TA, and uncastrated controls. In Trial 1,
pain-related behavior was assessed using a customized numerical rating scale (NRS) over 4 h. In Trial 2, pre- and postoperative skin sensitivity of the
wound and periwound areas was assessed using an electronic von Frey anesthesiometer (IITC Life Sciences, Woodland Hills, CA) and von Frey monofilaments (300 g). 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 on the basis of 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 uncastrated 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 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 in routine husbandry procedures.