OPTIMIZING MELOXICAM USE FOR PAIN MANAGEMENT IN CALF DEHORNING

Dehorning is a widespread practice on dairy farms, undertaken to remove horns or inhibit their growth. This procedure primarily aims to enhance safety for handlers and prevent injuries among herd animals. Recognizing that dehorning causes pain and discomfort, the American Veterinary Medical Association (AVMA) supports the practice yet strongly emphasizes the importance of effective pain management. While local anesthetics are frequently combined with non-steroidal anti-inflammatories (NSAIDs) for dehorning procedures, it is important to note that no FDA ­approved NSAIDs are currently specifically labeled for pain management in food animals.

The assessment of pain associated with dehorning can be attempted through various physiological and behavioral metrics. These include measuring concentrations of cortisol, haptoglobin, and plasma substance P (SP), monitoring ocular temperature, heart and respiratory rates, or observing physical restlessness and mechanical nociceptive threshold (MNT). However, a significant challenge remains since none of these methods are validated for precise pain scoring in cattle. Despite the availability of numerous drug options for cattle pain management that comply with the Animal Medicinal Drug Use Clarification Act of 1994, this discussion will specifically focus on a study that investigated the effects of meloxicam on calf stress responses.

An article published in the Journal of Dairy Science, research at Kansas State University in Manhattan, KS investigated the effect of meloxicam, given before and after dehorning, on calf pain and stress in response to dehorning. Thirty Holstein bull calves were randomly assigned to three treatments: 1) those receiving meloxicam 12 h before dehorning (MEL-PRE), 2) immediately after dehorning (MEL-POST) or 3) a placebo control (CONT). Blood samples were taken at multiple time points between 5 and 720 minutes, as well as 24 h, and 7 d post-dehorning, via the jugular vein. These samples measured the concentration of cortisol, SP, haptoglobins, PgE2, and the drug. An algometer was used to measure the mechanical nociceptive threshold, which is the minimum amount of pressure that can be applied to evoke an aversive response. This response was measured at three sites around the horn bud at various points between -1 to 720 minutes, as well as 24 h and 7d post-dehorning. Maximum ocular temperatures (MOT) were measured using an infrared inspection system. With these comprehensive measures in place, the study aimed to evaluate the efficacy of oral meloxicam on pain responses and determine if its administration 12 hours prior to a procedure is more clinically effective than immediate post-procedure administration.

The administration of meloxicam in the MEL-PRE and MEL-POST calves had a considerable impact on physiological indicators of pain and inflammation when compared to the CONT group. Interestingly, the timing of meloxicam administration (before or after dehorning) did not affect serum cortisol, substance P, haptoglobin, ocular temperature, or MNT. Specifically, at 4 h post-dehorning, calves treated with meloxicam were found to have significantly lower serum cortisol concentrations when compared with those who did not. Additionally, at 120 h post procedure, treated calves were found to have significantly lower SP concentrations than their untreated counterparts. Haptoglobin concentration increased over time for all three groups; thus, no treatment effect was observed. The study observed no significant effect of meloxicam administration, regardless of its timing, on the maximum ocular temperature of the calves. While the initial mechanical nociceptive threshold (MNT) was higher in control calves at 1 h post­dehorning, meloxicam-treated calves showed a trend towards a higher MNT at 6 hours. In contrast, the timing of meloxicam administration proved relevant when observing the concentration of Prostaglandin E2 (PgE2) in the treated and untreated calves. The concentration of PgE2 at 6 and 12 h was lower in the MEL-PRE and MEL-POST calves. However, at 24 h, the calves treated 12 h before dehorning (MEL-PRE) and the placebo control group (CONT), exhibited significantly higher Pgfa concentrations than those treated with meloxicam at the time of the procedure (MEL-POST); this trend was true for 3 days post­dehorning.

In summary, the study demonstrated that meloxicam effectively alleviates pain and inflammatory responses in calves post-dehorning. While several indicators of physiological stress were consistently reduced by the treatment, the precise timing of meloxicam administration proved to be a factor, particularly influencing the duration of certain anti-inflammatory effects. However, the impact of pre- or post- administration of meloxicam on varying time points may in PgE2 concentration may justify further research to fully understand and optimize the use of pain management drugs in this context. Overall, these findings highlight the benefits of meloxicam in managing post-operative pain in livestock.

—Hannah Jones

hjones@whminer.com