Iowa State Research On Dairy Goat Kid Disbudding.

 By J.K. Shearer and P.J. Plummer - Department Veterinary Diagnostic and Production Animal Medicine College of VBeterinary Medicine Iowa State University.

Based upon statistics compiled by the USDA APHIS, 64.4% of goat dairies disbud goat kids.  Most (95.8%) were disbudded with a cautery iron, lesser percentages with caustic paste (1.2%) and other methods (3%). The ideal time to conduct disbudding procedures is between 4 and 7 days of age. Beyond 2 weeks of age the procedure arguably becomes more of a dehorning rather than disbudding procedure. Although one of the least favorite tasks of dairy goat owners, they know that failure to remove horns risks injury to themselves and to the goat’s herd-mates.

Disbudding causes acute pain during the procedure and discomfort that lingers into the recovery period that follows. The cautery iron tip produces second or third degree burns in the skin around the site of the horn bud. In the worst-case scenario, cautery disbudding results in brain damage and death.

Strategies available to alleviate the pain associated with disbudding include sedation, general anesthesia, local anesthesia (either injection of lidocaine similar to that used for dental procedures in humans, or application of anesthetic cream to the skin like used for injections in human babies). Control of pain and inflammation in the period following disbudding is also an important objective.  Non-steroidal anti-inflammatory drugs, such as meloxicam, are often used to reduce pain and inflammation associated with the procedure.  Goat kids given meloxicam orally demonstrate fewer behavioral signs of pain such as isolation, stiff movements and head shaking during the first 24 hours following disbudding procedures.  

There is clear evidence that general anesthesia of kids during disbudding provides the best pain control; however, this is not generally feasible at commercial scale in the US due to the need for veterinary oversight of general anesthesia and the short window for disbudding. Some countries, including the UK, do require veterinarians to perform disbudding and general anesthesia. In the following we summarize findings from recent studies at Iowa State University on the effects of anesthesia and analgesia for the management of pain during disbudding of goat kids. And finally, since brain damage is a potential secondary complication of cautery iron disbudding, we share findings on our study of brain injury from cautery disbudding.   

Anesthesia and Systemic Analgesia for Cautery Disbudding
In an on-farm trial of disbudding dairy goat kids we evaluated the impact of a) injectable lidocaine local anesthesia (applied around the horn buds) and b) topical local anesthesia cream on the horn buds compared to standard cautery disbudding without additional local anesthesia. The results clearly demonstrated that injection of the local anesthesia resulted in pain responses in the kids that were not distinguishable from the pain directly associated with cautery disbudding without the local anesthesia.  In other words, the pain was similar between the methods and only differed in when the pain was experienced  - at the time of injection for the lidocaine anesthesia compared to at the time of disbudding. Based on these results and the prolonged period of handling required for the local anesthesia injection, we do not see significant value in routinely using local anesthesia injection during disbudding.

Contrary to what we expected, the local anesthesia cream did not show any reduction in pain, and in some goats actually seemed to make the pain more severe in some animals. Although we do not understand why this occurred, at present there is no evidence to support the use of anesthesia cream applied to the skin.

Brain Injury from Cautery Disbudding
In order to evaluate the potential for heat damage to the brain associated with prolonged application of thermal cautery to the bud, we performed general anesthesia on commercial dairy kids and then applied the cautery iron for 5, 10, 15 or 20 seconds. Several days later we evaluated the brain of the kid using MRIs to determine if there was damage to the brain.  Although none of the kids showed clinical evidence of brain damage, the MRI did detect some changes in the brain under the horn buds of some of the kids.  Application of the cautery iron of 15 seconds or greater resulted in more severe lesions (but again no clinical disease in the kids tested).  Based on these findings we suggest applying the iron for as short of a period possible, and ideally not more than 10 seconds per bud (see photos of brain lesions).

In conclusion, disbudding goat kids is an unpleasant, but necessary task for goat owners. The best time to disbud is between 4 to 7 days of age. There is little doubt that it is painful, but strategies to minimize the pain of disbudding in goat kids are far more complicated than disbudding in calves.  A ring block around the horn bud with local anesthesia with 1% lidocaine usually requires at least 2-3 subcutaneous injections. Each injection elicits discomfort and, in the study, reported here, did not prove to be an effective technique for minimizing the pain of cautery disbudding.  A veterinarian can use general anesthesia, which eliminates pain during the procedure, but is not without risks.  Finally, thermal brain injury is an important concern with cautery iron disbudding.  The skulls of goat kids are thin which makes the brain highly susceptible to injury with prolonged exposure to the cautery iron.  Application times of 15 s or more should be avoided.  

References:
Disbudding on U.S. Goat Operations, Management Practices Brief, November 2020, https://www.aphis.usda.gov/animal_health/nahms/goats/downloads/goat19/go... Accessed March 16, 2023
Hempstead, MN, Lindquist TM, Shearer JK, Shearer LC, Sutherland MA, and Plummer PJ.  Acute cortisol and behavior of dairy goat kids administered local anesthesia, topical anesthesia or systemic analgesia prior to cautery disbudding.  Physiology & Behavior, Volume 222, 1 August 2020, 112942
Hempstead MN, Shearer JK, Sutherland MA, Fowler JL, Smith JS, Smith JD, Lindquist TM, Plummer JP.  Cautery Disbudding Iron Application Time and Brain Injury in Goat Kids: A Pilot Study. Section Animal Behavior and Welfare, Front. Vet. Sci., 2021;18:1-9