Lumps known as papillomas or warts present on the skin and mucous membranes are benign (non-cancerous) masses most often caused by the papillomavirus group of viruses (Miller et al, 2003). Papillomas are conspicuous as firm, nodular masses fastened only to the skin and varying in diameter from 10 to more than 100mm. All are fleshy. Some are covered with gray or dark skin which often is scratched and bleeding. Others have a black, dry, hard surface that may be fissured much like the head of a cauliflower. The larger ones tend to be pendulous because of their weight and stem-like attachment to the skin. Papillomas can occur anywhere on the animal’s skin, but are more common on the head, neck and shoulders (Adrian, 1981). They may be single or multiple. A heavily infected deer may have 25 or more. Occasionally, in multiple infections, they are so numerous and close together that they join into a coalescent mass (Michigan, 2010).

Papillomas have been reported in white-tailed deer, black-tailed deer, elk and mule deer over much of their respective North American ranges. Similar skin tumors have been reported from moose on Isle Royale and in British Columbia (Michigan, 2010).

Papillomas can infect any mammal, but are found especially on cervids. These tumors are seen in both white-tailed and mule deer and occasionally in elk, pronghorn and moose. Other virus-caused tumors of wildlife include oral papillomas of coyotes, papillomas of the skin of rabbits, and fibromas of squirrels (Adrian, 1981).

Transmission occurs through direct contact with warts or lesions of an infected animal that contain virus particles. Transmission may also result when infective lesions are abraded by vegetation that is subsequently in contact with uninfected hosts. Bites of blood-feeding invertebrates (ticks, mites, mosquitoes, etc.) may also transfer the virus. In general, virus-caused tumors are quite species-specific and are unable to be transmitted to members of an unrelated species. Reports have described areas where several animals are affected over successive years (Adrian, 1981; Miller et al, 2003).

Affected animals have hairless wart-like growths on their skin. Growths can be quite variable in number (few to numerous), size (very small, 1-2 mm, to huge, 8–10 cm), coloration (light to dark) and texture (smooth to “cauliflower-like” in appearance) (Miller et al, 2003). On cross section, papillomas show a white, tough core of uniform texture covered with a rind of varying thickness and color. Those with a thin layer of skin show a thin and lightly pigmented rind, while those with a hard fissure external surface have a thick dark rind (Michigan, 2010). They are often found around the eyes and neck, but may also be on the body or legs. The growths are generally limited to the skin and are easily removed during skinning. These tumors frequently regress and, once the animal has recovered from them, there appears to be resistance to subsequent recurrence (Adrian, 1981). Animals are generally in good body condition but may become weak and debilitated if the number and size of tumors becomes unusually large or when tumors interfere with vision, mobility, or eating. Lesions may resemble those of poxvirus infection in birds (Miller et al, 2003).

Although unsightly, papillomas are of no consequence to human health as humans cannot acquire warts from non-primate wild mammals (Miller et al, 2003).

Is it safe to eat the meat?

In general, papillomas do not affect quality of the meat. If the papilloma extends into the underlying muscle, the area surrounding the mass should be trimmed and discarded.

Papillomas alone do not affect meat quality or safety; however, some animals with large ulcerated or abraded masses may develop secondary bacterial infections that do have potential to affect the quality of the meat. Some clues that the meat may not be fit for human consumption are:

1. animal is in poor body condition
2. animal has a foul odor
3. animal has enlarged lymph nodes
4. unusual color or consistency of the meat.

If you harvest an animal and are unsure whether it is safe to eat, contact your local FWP staff for guidance soon after the animal is harvested.

Adrian, W.J., editor. 1981. Manual of Common Wildlife Diseases in Colorado. Denver: Colorado Division of Wildlife.

Michigan Wildlife Disease Manual. 2010. Michigan Department of Natural Resources. Website

Miller, M.J.R., R.D. Dawson, and H. Schwantje. 2003. Manual of Common Diseases and Parasites of Wildlife in Northern British Columbia. University of Northern British Columbia.