By Chris Cook, Wildlife Biologist,Alabama Division of Wildlife and Freshwater Fisheries
Most deer hunters in Alabama have at some point either killed or seen deer with one or several large “tumors” on their head, neck, or body. When first observed, these growths cause concern in many hunters who wonder if the deer is carrying a disease that can affect the hunter or other deer in the area. Almost without fail, such growths turn out to be cutaneous fibromas.
Cutaneous fibromas, more commonly called deer warts, are hairless tumors found on the skin of white-tailed deer. Although the fibromas can be found on all areas of the body, the most common locations are the head, neck, and shoulders. The fibromas usually are black or gray in color and vary from pea-sized up to 8 plus inches in diameter. The surface of the fibromas is most often smooth and hairless, but can be wrinkled and “warty” in appearance. Deer may have a single small fibroma, or they can be covered with many of various sizes. Fibromas also can appear in large clumps.
Fibromas are caused by a virus. The virus is thought to be transmitted by biting insects, as well as direct contact with various contaminated materials that can penetrate or scratch the skin. Researchers have experimentally infected deer with the virus and found that the fibromas normally appear seven weeks after exposure, but usually start to regress after only two months.
An array of wart-like skin tumors can also appear on other wild cervids and domestic livestock. The causative viruses in livestock are different from the one found in white-tailed deer, therefore spreading of the fibromas from deer to livestock, such as cattle, sheep, horses, and rabbits, is not a risk.
Fibromas rarely cause deer any serious health problems, but occasionally their location can interfere with sight, eating, breathing, or even walking. Normally, the inside of a fibroma is firm and white, but occasionally, larger fibromas develop a bacterial infection through a break in the skin. Fibromas are typically only attached to the skin of the deer, but on rare occasions are attached to structures beneath the skin. Their presence typically is not detectable after skinning the deer.
No human infection from cutaneous fibromas has been reported. Hunters only concern should be from an animal with extensive bacterial infection in the fibromas, which would render the deer unsafe for human consumption. Animals in this condition would be readily apparent due to the unpleasant “ooze” produced at the infection site.
Cutaneous fibromas of white-tailed deer are merely skin blemishes, causing more concern to deer hunters than to the deer themselves. Although they can be unsightly, warty deer are of no significance to the long-term health of a deer population.