Ferrets: Mast Cell Tumors

Mast cell tumors are relatively common skin tumors affecting pet ferrets. In rare cases, these tumors can also be detected on the spleen.

They arise from a type of cell called a mast cell. In dogs, and less so in cats, these tumors can vary from benign to highly malignant. 

Fortunately, in ferrets, mast cell tumors are benign and do not metastasize (spread through the body). The average age for ferrets to develop mast cell tumors is four years old.

What do mast cell tumors look like?

Mast cell tumors might be mistaken for an insect bite. They are often present for months and may be ignored by owners because they tend to disappear and then return. In ferrets, mast cell tumors tend to fluctuate in size, but they are often 3/8-inch (1 cm) or less. They are often circular, flat, or slightly raised masses. 

These growths generally occur on the torso, but can be found on the face or legs too. Some tumors are itchy (pruritic) and may be visible after the ferret has scratched them. They may be ulcerated and bleeding, leading to a round sore and crusty scab with hair matted over top. If the scab falls off, the lesion may be red, oozing, and hairless. Once the scab falls off, the lesion heals, only to erupt several weeks to months later.

How are mast cell tumors diagnosed?

A mast cell tumor is suspected if the mass has the classic appearance described above. They can often be diagnosed by cytology: a microscopic examination of cells collected by tissue scrapings or fine needle aspiration of the tumor. A biopsy sample may be submitted to a laboratory for a definitive diagnosis.

Can mast cell tumors be treated?

Yes, mast cell tumors in ferrets can be treated. Complete surgical removal is usually considered curative. It is recommended to have histopathology done on the removed tissue to confirm the diagnosis. 

Unlike dogs and cats, ferrets with mast cell tumors rarely require medical therapy. New mast cell tumors may form in a different location, but recurrence is not due to metastasis or spreading of the initial tumor. If you detect any sore or skin lump on your ferret, you should have it examined by your veterinarian as soon as possible.