Gray squirrels exhibiting a grotesque appearance, characterized by oozing, wart-like tumors, have been increasingly observed in backyards across several U.S. states this summer. Sightings have been reported in Florida, North Carolina, and Michigan, among others, with numerous photographs surfacing on social media.
The condition, which causes hairless patches and gnarly growths, has led to concerns among residents, with some describing the afflicted animals as appearing deformed or "zombie-like." Wildlife experts suggest that the cause is likely squirrel fibromatosis, a viral skin disease caused by a leporipoxvirus.
Understanding Squirrel Fibromatosis
This leporipoxvirus leads to the development of tumors that can ooze fluid. According to experts, the virus spreads through direct contact between healthy squirrels and the lesions or bodily fluids of infected squirrels. This transmission method is similar to how herpes is spread in humans. The condition is sometimes confused with squirrelpox, a more common and potentially fatal disease affecting red squirrels in the United Kingdom.
While the skin condition often resolves on its own, severe cases can result in growths affecting internal organs, which can be fatal. The tumors typically heal within four to eight weeks, and experts advise allowing the animals to recover naturally.
Surge in Sightings and Potential Causes
A notable increase in sightings of squirrels infected with leporipoxvirus occurred in August 2025, with spikes observed in states like Maine and in parts of Canada. Experts suggest that a higher concentration of squirrels, potentially due to bird feeders, could facilitate the spread of the virus. When squirrels congregate to feed, infected animals can transmit the virus through saliva or other fluids left on uneaten seeds, exposing other squirrels.
Despite their alarming appearance, wildlife officials emphasize that these squirrels pose no threat to humans, pets, or birds. The primary concern is the transmission among squirrel populations. Residents are advised not to approach or handle the affected animals and to let them heal naturally.