by Miriam Martin, graduate student
Reducing pain at the time of castration is a topic that has received renewed interest in scientific meetings, in conversation with consumers, and is beginning to work its way into producer’s conversations with veterinarians. A lot of confusion surrounds extra-label drug use, what agents are available, the practicality of implementing preemptive analgesia, and whether or not it’s right for your operation. There are currently no compounds specifically approved for pain relief from castration in livestock in the U.S. Thus, the use of such compounds is extra-label drug use and requires that drugs be administered by or under the supervision of a veterinarian. Yet, it’s important to remember that the American Veterinary Medical Association supports the use of procedures that reduce or eliminate the pain of castrating cattle. Lidocaine and flunixin meglumine are the only compounds with analgesic properties that are approved by the FDA for use in cattle in the U.S.
Decreased plasma cortisol concentration after castration is associated with preemptive administration of a nonsteroidal anti-inflammatory drug (NSAID) and local anesthesia. Local anesthesia such as lidocaine alone tends to lessen acute stress. NSAIDs alone reduce the release of cortisol over time more than a local anesthetic would do alone. Ideally, a multimodal approach of both an NSAID and a local anesthetic are the most effective at mitigating pain from castration. Response to pain from castration consists of two phases. The initial response is brief, localized, and related to the intensity of the trauma. This being the immediate incisional phase. The second phase is the prolonged, diffuse inflammatory phase. The goal of administering analgesia is to mitigate the pain response to both of these phases.
One challenge that exists is that local anesthetics require 2-5 minutes before a maximal effect is achieved. Another challenge in the past has been the route of administration for an analgesic drug. The recent availability of the NSAID flunixin transdermal now allows for more practical application of an NSAID, by administering the analgesic along the midline of the animal’s back. In a recent study conducted at the K-State Stocker Unit it was found that co-administration of tildipirosin (Zuprevo) and flunixin transdermal (BANAMINE Transdermal) upon arrival to the feedlot at the time of castration resulted in lower visual analog scores indicating less pain the first 36 hours after drug application than calves given tildipirosin alone. Transdermal flunixin has been found to reduce plasma cortisol and mitigate the stress response for 8 hours when given at the time of castration. It has also been shown that calves administered the NSAID meloxicam before castration had a reduced pen-level first pull rate and reduced bovine respiratory disease (BRD) morbidity rate. The NSAID meloxicam when administered in post-weaning calves before castration ultimately reduced the incidence of BRD at the feedlot.
Regardless of whether or not an anesthetic or analgesia is used at the time of castration, the age of the calf also matters. A simple rule to remember when deciding upon age of castration is that younger is better. Calves banded at weaning have been found to gain less weight than those surgically castrated at 2-3 months of age and when cattle were castrated from 8-14 months of age they had poorer growth rates than those castrated at weaning. Studies show that banding especially in older cattle elicits higher plasma cortisol responses for longer periods. Yet, in a study of bovine practitioners 89% of respondents indicated that they were castrating heavy weight calves over 600 pounds. Finding ways to reduce age of castration will likely result in more weight gain.
Bovine practitioners when surveyed identified swelling, stiffness, and increased lying time as the most prevalent adverse events following castration. Over half of respondents were using disinfectants, prophylactic antimicrobials, and tetanus toxoid to reduce the occurrence of complications following castration. Surgical castration wounds have been shown to take between 10 and 61 days to heal. Good management practices such as reducing the age of castration and using disinfectants when castrating also contribute to the overall health and well-being of calves following castration.
When surveyed, only one in five bovine practitioners reported using an analgesic or local anesthetic at the time of castration in 2010. The proportion of practitioners using an analgesic or local anesthetic has likely evolved and will continue to change, in particular if compounds become approved for pain relief from castration in livestock in the U.S. in the future. Starting a conversation with your veterinarian about pain relief during castration and understanding what compounds are available for use with veterinary oversight are the first steps. The combination of castrating at a young age, using disinfected equipment during castration, and administering an analgesic and/or local anesthetic under the oversight of a veterinarian will likely result in castration that is the least stressful for the calf and promotes them being the healthiest and most efficient down the line. By implementing even one of the afore mentioned practices into your operation, you can move one step closer to a less stressful castration process for the calf and improved animal health and well-being.