Dehorning & Pain Control

Cornual nerve blocking

Use of pain control methods during dehorning by veterinarians and calf raisers has been increasing, especially since dehorning was identified by the National Dairy FARM program as a medical procedure requiring pain management. Even so, adoption and use of consistent practices is not part of dehorning protocols on many farms.

Three research studies that evaluated different aspects of dehorning and pain control have recently been published in the Journal of Dairy Science:

The first paper (1) was a meta-analysis that looked across the published research for trials on dehorning and pain control to examine the effects of pain control practices for cautery (burning) dehorning. This is the most common method for dehorning calves. Twenty-three research trials were included in the evaluation. The outcomes the authors were able to look at were plasma cortisol concentration, pressure sensitivity of the horn bud area and pain behaviors (ear flick, head shake, head rub, foot stamp and vocalization). These measures provide insights into stress as well as the presence and degree of pain sensations.

cautery dehorning

Cornual nerve blocking with a local anesthetic prior to cautery dehorning was associated with a reduction in plasma cortisol up to 2 hours after the procedure with a rise in plasma cortisol occurring around 4 hours post-dehorning. Administering an NSAID such as oral meloxicam in addition to the local anesthetic prior to the procedure was correlated with lower plasma cortisol at 4 hours and also reduced pressure sensitivity of the horn bud area and pain behaviors for 3 to 6 hours after the procedure.

Elevated plasma cortisol is not necessarily a bad thing. Higher levels of cortisol over time can stimulate appetite, which could prove useful for a calf that needs additional nutrients to help repair tissues disrupted by dehorning.

The study demonstrates that administering a local anesthetic provides a protective effect for the acute pain associated with cautery dehorning, and administering an NSAID can delay the rise in serum cortisol and reduce other signs of pain. Based on these findings, effectively mitigating the pain that calves experience during and after cautery dehorning requires use of both a local anesthetic to block the cornual nerve, such as 2% Lidocaine, and administration of an NSAID such as oral meloxicam 10-15 minutes prior to the dehorning procedure.

The second paper (2), which also looked at the effects of cautery dehorning, evaluated pain sensitivity and growth parameters of calves dehorned at either 3  or 35 days of age. It took about 9 weeks for the cauterized tissue to heal over and increased pain sensitivity was observed throughout the 9 week period. No effect was observed on average daily gain, but a difference in sensitivity to pain was observed between calves dehorned at 3 and 35 days of age. Calves dehorned at 3 days showed greater sensitivity to pain when pressure was applied to the wound. There was also evidence that these calves had greater pain responses when pressure was applied elsewhere on the body. Although there does not appear to be an advantage to dehorning at 3 days of age, there is thought that subjecting the calf to such a painful procedure at this time may produce a generalized long-term increase in pain sensitivity compared to calves dehorned at a later age.

Caustic paste dehorning

The third paper (3) evaluated the effects of different dehorning procedures on pain measurements in dairy goats. Serum cortisol concentration and skin temperature of the horn bud area were used as indicators of pain and stress. No pain control methods were used.

The researchers found that the dehorning method used did not influence weight gain. Kids that were dehorned with caustic paste had higher serum cortisol levels and higher skin temperature measurements after the procedure than with other dehorning methods, indicating caustic paste caused more pain than cautery dehorning. Caustic paste also caused greater tissue damage.

Conclusions

The accumulated research evidence clearly emphasizes the need for providing animals with both local anesthesia to reduce the acute pain associated with the dehorning procedure and administration of an NSAID to reduce post-operative pain. That’s true regardless of dehorning method used. They all cause significant pain. In addition, there does not appear to be any pain mitigation or performance advantages by dehorning at a very young age, and it may be that early dehorning may increase long term sensitivity to pain.

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References

1. Winder, C. B., C. L. Miltenburg, J. M. Sargeant, S. J. LeBlanc, D. B. Haley, K. D. Lissemore, M. A. Godkin, and T. F Duffield. 2018. Effects of local anesthetic or systemic analgesia on pain associated with cautery disbudding in calves: A systematic review and meta-analysis. J.Dairy Sci. 101:5411-5427.
2. Adcock, Sarah J. J., and C. B. Tucker. 2018. The effect of disbudding age on healing and pain sensitivity in dairy calves. J. Dairy Sci. 101:1-13
3. Hempstead, Melissa N., J. R. Waas, M. Stewart, V. M. Cave, and M. A. Sutherland. 2018. Evaluation of alternatives to cautery disbudding of dairy goat kids using physiological measures of immediate and longer-term pain. J. Dairy Sci. 101:5374-5387.

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