Effects of Timing of Local Anesthesia on Physiological Responses in Calves after Dehorning

The American Veterinary Medical Association has stated the importance of minimizing pain associated with dehorning to limit the amount of distress and changes in the animal’s behavior and physiological states (AVMA, 2014b). The following studies aim to determine the effect of timing of lidocaine administration on physiological responses in calves after dehorning. The first study compared cortisol and substance P levels in calves dehorned immediately after administration of lidocaine and meloxicam, calves dehorned 10 minutes after the administration of lidocaine and meloxicam, and calves that were administered lidocaine and meloxicam and not dehorned. It was concluded waiting 10 minutes after administration of lidocaine and meloxicam to dehorn calves provided no benefits, as it did not reduce plasma cortisol and substance P compared to other treatment groups. The second follow up study compared cortisol and adrenocorticotropic hormone (ACTH) levels in calves dehorned immediately compared to calves dehorned 10 minutes after the administration of lidocaine alone, calves dehorned without lidocaine, and calves administered lidocaine but not dehorned. Waiting 10 minutes to dehorn calves after lidocaine administration may provide some benefits in reducing plasma ACTH and cortisol. Calves dehorned after a 10-minute waiting period had lower peak plasma ACTH levels and reached pretreatment levels for both plasma ACTH and cortisol quicker than the other treatment groups that were dehorned. However, differences observed in ACTH dissipate in 5 minutes and all calves reached baseline plasma cortisol levels within an hour of dehorning