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Large tumors on squirrels #921794

Asked November 11, 2025, 11:18 AM EST

Since moving back to Macomb County I have noticed a few squirrels with large tumor-like growths. What is this, and should I be concerned about the possibility of environmental pollution as the cause?

Macomb County Michigan

Expert Response

Hello,

Though I can't diagnose precisely what you are seeing, it may likely be Squirrel Pox, which the Michigan DNR provides more information about in the link below. 

https://www.michigan.gov/dnr/managing-resources/wildlife/wildlife-disease/wdm/squirrel-pox

This is not caused by environmental pollution.


Best, 

Clay Wilton (he/him) Replied November 13, 2025, 11:05 AM EST

Before contacting you, I looked up conditions and saw many photos of Squirrel Pox. They all seem to be much smaller growths and different in color. This is one large (quarter sized) round, black, smooth-looking tumor under the squirrel's mouth/chin, which has grown noticeably larger since August.  Other than that large growth, the squirrel seems active. Regardless, I've removed the bird feeders.  Thank you.
From: ask=<personal data hidden> on behalf of Ask Extension
Sent: Thursday, November 13, 2025 11:05 AM
To: Anne Graber
Subject: Re: Large tumors on squirrels (#0191710)
 
The Question Asker Replied November 14, 2025, 12:00 PM EST

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