What are those dark growths on that deer?

The growths in the image above appear to be cutaneous fibromas.

What causes cutaneous fibromas?

Cutaneous fibromas are wart-like, hairless tumors caused by a virus. The virus, which is species specific, poses no known threat to humans.  In deer the viruses that cause fibromas are probably transmitted primarily through broken skin. Deer become infected when an area with broken skin comes in direct contact with an infected deer or with a surface that an infected deer rubbed against. Biting insects may also be able to transmit deer fibroma.

How much do fibromas affect deer?

Fibromas are restricted to the skin of deer and do not spread to internal organs. The impact of fibromas on the health of the deer varies depending on the number and size of the skin masses. If fibromas are small and few in number, the deer’s immune system can take care of the tumors and they resolve spontaneously without significant impact to the health of the deer. In most cases, fibromas are small and resolve on their own.

However, occasionally fibromas can become large or numerous, at which time they may significantly impact the health of the deer, either by interfering with sight, respiration, eating or walking or they may become ulcerated resulting in secondary bacterial infections. When fibromas are large, numerous, or in critical locations (eyes, mouth, etc.), they can result in significant disease and death.  There is no treatment for fibromas in wild deer.

Is the meat safe to eat?

The virus associated with fibromas does not infect humans. Deer carcasses with fibromas that do not have evidence of secondary infections would not pose a threat to human health. The venison would be safe to eat if properly prepared and cooked. Yet, fibromas with evidence of secondary bacterial infections would be unfit for human consumption.

You can find more information on cutaneous fibromas on the Game Commission website.

-Bureau of Wildlife Management

Photo provided by Anna Marie