Injection of isoeugenol to prevent horn growth as an alternative to thermal dehorning in calves - a field study

Introduction Calves are frequently disbudded due to management factors or to reduce the number of injuries from their horns to other animals and farm workers. The most common method is thermal disbudding, which leads to pain and slowly healing wounds. The literature describes injection of clove oil and isoeugenol as preventing horn growth. We have evaluated the success of the injection of isoeugenol, by local vets on the farms. Materials and methods Thirteen different veterinary practitioners injected 2.5 ml isoeugenol under each horn bud of 88 calves (younger than 4 days). The site of injection was chosen according to Schoiswohl et al. (2020, 2022). Horn growth was monitored for 6 months and if the horns did grow horn length was measured by the farmers. Results After six months, 89 horns showed no growth, while 41 horns grew by 0.5-4 cm. On request of the owners, 28 horns were thermally removed after 3 to 5 months, by which time they had grown 1-2 cm. The data of 18 horns were not complete and thus not evaluable. Conclusion Practitioners are able to apply this alternative disbudding technique in a short time. Horn growth was substantially decreased after treatment with isoeugenol. In cases where horn growth was not completely suppressed, it was significantly reduced. As the risk of injuries caused by small horns is substantially decreased, such cases can also be considered as disbudding success.