Reprinted from the Tracker, volume 4, issue 9, October 2000
At a recent meeting of the Code of Practice for the Care and Handling of Farm Animals-Bison committee, dehorning created a lot of discussion. Is dehorning bison necessary at all? If it is, what is the proper way to do it? In this article I will discuss dehorning bison and attempt to present both sides of the discussion so that you can make your own decision as to what is right for your bison.
Advantages and Disadvantages
The advantages of dehorning include:
- safety for other bison in the herd. Many bison have been gored by a herdmate while crowded in a handling facility.
- safety for the farmer (if they ever get charged by a bison)
- less space is required at the feeders (hay or grain) because dehorned bison tend to tolerate each other's presence better
- less injuries due to bruising and goring during transportation
The disadvantages of dehorning include:
- stress and pain caused to the animal during and after the procedure
- reduced weight gains for several weeks after dehorning
- risk of infection in the skull sinuses (holes left behind when horns are removed from larger animals)
- risk of excessive bleeding
- reduced ability to protect themselves from predators
- destruction of the natural look of bison
- increased holding time in the squeeze. Some producers feel that this will cause excessive stress and occasionally death in bison
It is up to individual producers to decide if dehorning makes sense in their herd. If herds are kept in a large area, graze all year, and are not crowded during handling, dehorning may not be necessary. If the bison are more intensively reared, dehorning may have advantages. Some people advocate removing the tips of the horns only. This may be good alternative. It removes the sharp and dangerous point so that there is less chance of a serious injury. It is a painless procedure because only horn tissue is cut and the underlying bone core is not disturbed. Research into this area is needed to determine if this is a good alternative.
Dehorning is usually less stressful on young animals. The horn is less developed in calves so it is easier to cut. The sinuses in the skull are also less developed and therefore there is less chance of opening the sinus. It may not be practical to dehorn newborns but doing them at the earliest convenient time makes sense.
There are many tools that work well for this job. Small horns can be removed with gougers (Barnes dehorners) that scoop off the horn. Larger horns can be removed with a guillotine-type dehorner (Keystone dehorner), a wire saw pulled by hand, or an electric dehorning saw. My preference is the wire saw (unless I am doing a large number) because it is the safest. The guillotine-type can be dangerous for you if the bison is swings its head. It can also crack the skull if the animal moves while you are cutting. The electric saws are quick and efficient but you have to be careful that you don't cut off other things such as ears, fingers, tags, etc.
A good job of dehorning will:
- remove the entire horn close to the head
- remove a ¼ inch of skin at the base of the horn. This removes the tissue that produces horn and therefore eliminates future growth
- not leave small pieces of bone behind. Sometimes gougers and guillotines will break off tiny bone fragments that are left behind in the wound. These fragments will slow the healing process and predispose the animal to infections
- not leave a hole into the frontal sinus of the skull but this is hard to if you want to cut the horns off close to the skull. Some bison producers will purposely leave 1-2 inches of horn attached so that they do not enter the frontal sinus and predispose the bison to an infection.
There are two main complications of dehorning. One is excessive bleeding. There are many ways to control bleeding after the horn has been removed. The simplest is to let the blood clot on its own. This usually works but sometimes animals bleed excessively. I prefer to control the bleeding before letting them out of the squeeze. The technique that I use is cauterization of the horn base. I use an electric dehorner but any hot metal object would work. The searing action of the heat seals the vessels and also destroys any horn producing cells that might be left behind after my cut. It is also quick. Most times it only takes a minute or two. Other methods are grasping vessels and twisting them, tourniquets, and blood stop powder. I find these awkward, slow, and not very effective.
The other complication is infected frontal sinuses. If debri gets into the hole, it carries bacteria with it and can start an infection. These infections can be successfully treated but require a lot of work. The best way to prevent this is to keep animals away from large hay bales while the wounds heal. This stops the animal from sticking its head into the hay and allowing feed to fall into the holes. I like to put animals back onto pasture or feed them on the ground after dehorning.
The best time to dehorn is in the fall or winter when flies are not around. Certain types of flies are attracted to open wounds. They can create infections or lay their eggs in the wound. It is best to avoid dehorning during the warm months of the year.
Horn removal is a painful procedure, especially when it is done in older animals. For the welfare of the animals I believe that bison farmers should consult with their veterinarians about use of analgesics for pain relief. Local nerve blocks are simple and effective. Electroanalgesia may work in bison. Injectable analgesics could be used to reduce the pain after the horns are removed. It has been suggested that the increased holding time in the squeeze is detrimental to bison and that cutting off the horns quickly and letting them go is better for the bison. This is another area where research is required.
I believe that you should carefully consider whether or not to dehorn your bison. It is a decision that requires careful thought. Hopefully this article will assist you in making your decision.