Calf Dehorner

Horned cattle are not only dangerous to people working with them, but cause a great deal of damage to hides. Should one or more cattle in a group sent to an abattoir for slaughter have horns, the probability of bruised carcasses is very high. Dehorning or using polled bulls prevents these problems.

Dehorning can be done by

• hot iron cautery of the horn bud (electric, gas and fire-heated irons are available)
  
• cautery using chemical pastes
  
• removal of the horn or horn-bud surgically, for which various instruments are available.

The most convenient method of dehorning is cauterisation of the horn bud when calves are 4 to 6 weeks old using a hot iron. Dehorning irons have a cup-shaped hollow in front which fits over the horn bud. To prevent flaming caused by the hair catching light and to make the horn bud visible, the hair around the bud is clipped using sharp scissors. After heating the dehorning iron to the right temperature (the iron can be tested on a plank and must provide an immediate black burn), it is firmly pressed over the horn. By holding the iron at an angle and moving it around in a circulate motion, the skin right around the horn bud is cauterised. The objective is to cause the skin under and around the horn bud to die, preventing horn-growth. Care should be taken to ensure that the hot iron is not held against the calf’s head too long because brain damage can cause death. Five seconds is usually enough time to achieve effective cautery.

Chemicals, usually included in a paste, are available for chemical dehorning. Because chemicals that burn can damage eyes and other parts of the skin, especially if unexpected rain washes the chemicals down over the face, care is needed in their use.

In older animals, surgical procedures must be used, especially if horns have grown to a length of 2 cm or more. Hot iron dehorning can usually be done with ease up to the age of 2 to 3 months (while the dehorning iron still fits over the bud comfortably), whereafter horn growth is fairly rapid, making surgical removal necessary. The removal of larger horns causes a great deal of pain and anaesthetics should be used with dehorning and steps taken to prevent bleeding. Blood attracts flies and blow-fly strike causes serious problems in open wounds. Once horns have grown very large, removal of the horns exposes the hollows in the skull and these must be closed to prevent infection. When a horn is removed surgically, using a dehorning iron to cauterise the skin around the base of the horn will prevent the possibility of horn tissue growing again and the hot iron can be used to prevent bleeding by cauterising bleeding blood vessels.

It is noteworthy that dehorning is stressful to animals. To reduce losses, the right age (younger animals have small horns requiring small procedures) and season should be selected for dehorning. Thus winter would have less problems with blowfly strikes, but animals are usually relatively old by the time they reach their first winter. Dehorning in early summer and treating for flies at the same time is a useful strategy to overcome this problem. Circumstances should also be taken into consideration. Where animals are bought and some cows have not been de-horned, a good strategy would be to dehorn younger cows, but leave older cows who will be sold in the near future in any event.