Strange wartlike growths in deer linked to same virus family seen in rabbits and squirrels

Across the U.S., deer are turning up with large, wart-like growths on their bodies — the latest species to show signs of viral skin disease that has also been documented in rabbits and squirrels this year.

Deer across several states are being photographed with large wartlike growths on their faces and bodies. They are the latest wildlife species showing signs of a virus that has also affected rabbits and had people talking about 'zombie squirrels' this year.

The condition, known as cutaneous fibroma or “deer warts,” is caused by a papillomavirus, the same viral family that led to outbreaks in rabbits (Shope papilloma virus) and squirrels (fibromatosis) earlier in 2025.

What’s happening in the field

Reports and photos posted to social media from New York, Pennsylvania, Wisconsin and other states show deer covered with clusters of gray or black tumors, sometimes as small as a pea and in other cases as large as a football.

“These are caused by viral infection, cannot be transmitted to man, and are seldom very injurious to the deer,” wrote longtime Deer & Deer Hunting field editor Leonard Lee Rue III, who has tracked the condition for decades.

How the virus spreads

Wildlife veterinarians say the papillomavirus is transmitted mainly by mosquitoes and ticks, which thrive in late summer and fall. “Papillomas are most frequently seen during the late summer and into the fall, probably due to increased biting insect activity during this time of year,” according to the Washington Department of Fish & Wildlife.

Deer can also spread the virus through direct contact at feeding sites or rubbing posts, especially during the rut.

Impact on animals

Most deer survive without long-term harm, and the growths typically fall off once they outgrow their blood supply. In severe cases, large clusters can interfere with eating or block vision, but the disease is rarely fatal.

Wildlife officials note that while the condition looks alarming, it has been documented in North America for decades and does not appear to reduce overall herd health.

Human health and hunting safety

Experts stress that papillomaviruses are species-specific: deer strains infect only deer, rabbit strains only rabbits, and so on. They cannot jump to people or other animals.

For hunters, the growths are removed with the hide during processing, and venison is safe to eat. Standard precautions, including wearing gloves, discarding affected tissue, cleaning equipment, and cooking meat thoroughly, are recommended.

Climate and social context

Researchers point out that climate change is extending mosquito and tick seasons, allowing viruses like these to spread further and last longer. At the same time, social media has amplified awareness, with graphic images of infected animals circulating widely this summer.

“These temperature changes are resulting in diseases that were never endemic in certain areas to become endemic,” said Dr. Omer Awan of the University of Maryland School of Medicine told Daily Mail.

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