Late Horn Removal
Miller, DVM, PhD
The horn of the goat is a bony core that is an extension of the frontal bone of the skull itself, surrounded by a horny covering produced by germinal cells in the skin all around the base of the horn. The hollow space inside the bony part is an extension from the frontal sinus. Arteries run in in the bony part of the horn, which is living tissue, and come from the skull. Nerves also run on the bony part and branch from two nerves that emerge onto the surface of the skull near the eye socket (orbit). One emerges from behind the bony extension that forms the posterior/lateral rim of the orbit, and the other emerges from the dorsal/medial corner of the orbit and can be felt in some goats. The horny layer is dead tissue similar to fingernails or hooves. The germinal cells that produce the horny layer are in the skin at the base of the horn and must be removed during the dehorning/disbudding process or they will continue to form horn material or scurs.
In the skin between and slightly behind the horns are the two musk glands responsible for the characteristic buck odor. Unless one wants the buck to smell good to the does, these glands are also removed at dehorning/disbudding.
At the point where the horn is attached to the skull there are two full layers or sheets of bone forming the roof and floor of the frontal sinus. Immediately under the floor of the frontal sinus is the brain cavity. Since the base of the goat horn is so broad, a flat plane that would remove enough germinal tissue to prevent scur formation would also remove a piece of the brain. Therefore, the cut needs to be curved so that only the outer layer of the skull is removed.
After dehorning you will be able to look into the frontal sinus through the hole in the surface of the skull. The bony edge of the hole gradually grows toward the center and is covered by normal skin, but this takes a long, long time. It is much better for everyone concerned to burn the horns off in a week-old kid rather than have to surgically remove them.
If scurs do form because not all the germinal tissue is
removed, you will have to decide to live with scurs or repeat the procedure.
Fortunately, the amount of germinal tissue left is much less than before and
the scur usually is not attached to bone. Normally, scur removal involves
cutting off the scur along with just the skin it is attached to with no bone
involvement. If the scur is not loose, however, there may be a need to cut
To dehorn an adult animal, chemical restraint is necessary. Various combinations of Ketamine and Xylazine have been recommended. Talk with your veterinarian about dosages and application because he/she is not allowed to provide these drugs without a valid doctor/client relationship. A comon regimen is 0.22 mg/kg of xylazine IM followed 10 minutes later with 11 mg/kg of ketamine IM. In case of an overdose with xylazine, yohimbine is an effective antidote. This combination gives you about 45 to 60 minutes of anesthesia. Use of other drugs in addition, such as acepromazine and atropine have also been used.
Another option is to anesthetize the nerves to the horn. As mentioned above, each horn has two nerves, one that comes from the dorsomedial margin of the orbit, and the other from behind the suproaorbital process, the ring of bone that comprises the posteriolateral edge of the orbit. Clip the hair from around the base of the horn removing enough to expose the musk glands. Inject 1 to 2 ml of 2% lidocaine solution into each of these two areas. Again, this is best left to a veteriarian or done under his/her/supervision as lidocaine can produce reactions in goats.
Use either a flexible hacksaw or, preferably, obstetrical wire to remove the horn at its base, including a circle of skin completely surrounding the base of the horn. This allows you to make a cut that follows the curvature of the skull thereby decreasing the chances of entering the brain cavity. Make sure you remove at least a thin strip of skin from all around the base. If any of this germinal tissue remains, it will produce scurs.
In removing the horn you will cut several arteries that run within the bone itself. Grasp these arteries with a forceps and pull them until they break off inside the bone. The clot that forms will prevent further bleeding. You will have created a hole into the frontal sinus. Cover or plug the hole with clean gauze that is changed daily until the wound heals. Daily sprays of furacin [now banned for use in goats - Maxine Kinne, editor] or Topazone TM are also indicated, especially for the first week or so.
This hole will require a long time to heal shut, but eventually it will fill with bone and be covered with skin. For this reason dehorning is best done soon after the fly season is over to prevent fly maggots from appearing on the wound or in the sinus. Another reason to keep it covered is to prevent dust and hay chaff from falling into the sinus cavity and causing an infection. If the sinus does become infected, daily drainage by twisting the head so the fluid runs out the hole followed by topical antibiotic application in the form of furacin spray or mastitis treatment is indicated. Do not use any of the preparations containing Gentian violet or other pretty-colored disinfectants because they damage the living cells of the sinus musoca as much as they do the bacteria.
Getting all of the horn base requires practice, so be prepared to remove any scurs that may eventually form.
|Dan Miller is a veterinarian with a specialty in small ruminants and parasites. He has worked with goats since he was in the Peace Corps in 1974. He is currently teaching veterinary medicine and doing research in parasitology at the veterinary college in Monterrey, Mexico. He received his DVM from Cornell University and his PhD from Texas A &M.|
Home Articles Links