Grotesque squirrels covered in oozing sores have been spotted invading backyards in the US, and a common garden object is helping the animals spread their condition.
The disfigured squirrels have been spotted in both the US and Canada in recent months, with social media users on both X and Reddit trying to figure out what’s wrong with the rodents.
The reports date back to 2023, when residents in Maine captured images of common gray squirrels covered in tumors while visiting their backyards.
Witnesses have photographed these hairless growths oozing pus covering most of the animals’ bodies, from their heads and eyes to their legs, feet, and genitals.
While some on social media have suspected that the animals are carrying squirrel pox, a rare virus in the US that mainly affects red squirrels, others have pointed out that the illness is more likely to be squirrel fibromatosis.
This condition is caused by a different virus, resulting in wart-like growths that may ooze fluid but usually heal on their own, and is more common in US gray squirrels.
In either case, wildlife experts believe homeowners who put bird feeders in their yards may be unintentionally causing the virus to spread to more squirrels throughout North America.
Shevenell Webb from the Maine Department of Inland Fisheries and Wildlife said: ‘It’s like when you get a large concentration of people. If someone is sick and it’s something that spreads easily, others are going to catch it.’
In November 2024, a Reddit user in the US posted an image of a squirrel covered in tumors consistent with squirrel fibromatosis
Squirrel fibromatosis is caused by a virus that cannot be transmitted to people or other animals
Squirrel fibromatosis may look terrifying, but it’s a common skin disease among gray squirrels in the US.
It’s caused by the leporipoxvirus and is spread through direct contact between healthy squirrels and the lesions or saliva of infected squirrels, similar to herpes transmission in humans.
The disease causes hairless growths or tumors, which can break open and leak clear fluid just like an open wound.
Although the virus cannot spread to humans or other animals such as dogs or birds, Webb said people should not touch or attempt to help infected squirrels.
‘I would not recommend trying to capture a squirrel that has the virus,’ Webb told the Bangor Daily News. ‘It is naturally occurring and will run its course in time.’
To Webb’s point, while the growths can look alarming, they typically heal without the need for medication and are rarely fatal.
However, some severe cases of squirrel fibromatosis may affect the animal’s internal organs and lead to death.
While sightings of infected squirrels date back to the summer of 2023, the most recent cases were posted online less than a month ago.
Residents in Canada have also captured images of infected squirrels who were covered in hairless tumors
The cases are not believed to be squirrel pox, which generally infects red squirrels and is more common in the UK
‘At first I thought it was eating something from my front beds, but then I realized it was on its face,’ one Reddit user posted on July 31 after spotting a gray squirrel with a large tumor on its mouth.
Wildlife officials noted that sightings tend to rise during the summer when more animals are out gathering food, especially from homes that put out bird feeders.
‘Like a lot of people, I love watching birds,’ Webb said. ‘Unfortunately, you can attract multiple [squirrels] to that feeder and risk exposure if one has the virus.’
The expert explained that squirrels with fibromatosis can leave their saliva on uneaten bird seed at these feeders, which healthy animals can then ingest and contract the virus.
To this point, wildlife experts have not confirmed whether the new sightings are cases of fibromatosis or squirrel pox (SQPV), but there’s less of a chance that squirrel pox is spreading through the US.
SQPV is a systemic condition that often results in death among red squirrels, who are more vulnerable to the virus. Moreover, SQPV is more common in the UK, as there are more red squirrels in that country compared to the US and Canada.
Fibromatosis tumors typically heal on their own within 2 months and do not return among gray squirrels
A similar condition affecting rabbits in the Midwest has prompted many on social media to ask if it would be humane to euthanize animals spotted with these tumors.
Just like the rabbits infected with cottontail papilloma virus, causing tentacle-like tumors on their heads, wildlife officials have said that people should leave squirrels with fibromatosis alone.
A squirrel’s immune system can clear the virus within four to eight weeks, although it may take longer for larger or secondary infections to heal.
The condition does not typically come back once a squirrel contracts fibromatosis, and gray squirrels generally recover fully, meaning the horrifying growths won’t be visible by the time people see that same animal next year.
