Unfortunately, ferrets are very prone to a wide variety of cancers. This is in part due to genetics; while breeders have been trying to “breed out” cancer prone lines, efforts have had limited success due to the restricted gene pool of the domestic ferret. Many breeders have outcrossed to wild EU polecats, but polecats often have an unknown genetic background, and are similarly prone to cancers, so while this has helped to improve some areas of health, cancer has continued to present an ongoing problem in ferrets. If you name a type of cancer, odds are a ferret can develop it. Indeed, ferrets are often referred to as “cancer machines” by veterinarians and ferret enthusiasts alike.
While ferrets can develop many, and indeed almost any, type of cancer, there are some cancers that are particularly common in ferrets. Below is a brief review of a few of the common cancers.
For more in depth discussion, refer to our several pages on Insulinoma. In brief, a genetic predisposition in conjunction with chronic stress on the pancreas due to carbohydrates in the diet leads to the eventual development of insulinoma in many ferrets. The strained pancreas is forced to produce insulin in excess of normal, physiologic amounts. Over time the beta cells of the pancreas increase in activity level, size, and number, until eventually cancer may form. Insulinomas may be microscopic to tumors visible to the naked eye (in imaging and surgery).
For more in depth discussion, refer to our several pages on Adrenal Disease. In brief, a genetic predisposition in conjunction with chronic stress on the adrenal glands due to early neutering and unnatural light cycles leads to the eventual development of Adrenal Disease in many ferrets. The chronic stress on the adrenal glands leads to overactivity, enlargement, and with enough time eventual tumor growth of the adrenal glands.
Lymphoma is one of The Big Three ferret cancers, and is the third most common cancer in ferrets, after Insulinoma (#1) and Adrenal tumors (#2). Lymphoma may present in any ferret, at any age, and with almost any symptom, or no symptoms at all.
Symptoms, when they do occur, are generally very non-specific and include (but are not limited to) symptoms such as reduced energy, reduced appetite, fluid retention, respiratory difficulties, weakness (usually generalized), GI distress including nausea and diarrhea. Some owners note a lump from an enlarged lymph node, or a vet may notice a mass on imaging. An enlarged spleen is common in lymphoma, but is also a common benign, incidental finding and may be unrelated to the presence of any type of cancer or disease.
Diagnosis can be difficult due to the varied presentation of the disease, and many ferrets are not diagnosed until a necropsy is done after their death. The best, and only definitive diagnostic test is to obtain a sample (i.e. aspiration or biopsy of of an enlarged lymph node or concerning mass) to send to pathology. Some lab findings may raise suspicion of lymphoma – in particular lymphocytosis (high lymphocyte count on WBC), anemia (low hemoglobin and hematocrit) and elevated protein and albumin levels – though these are not diagnostic in themselves, and may be absent even when lymphoma is present.
Treatment may depend on many factors, including the type of lymphoma, the age and health status of the ferret, and the budget of the owner. The most commonly used treatment is steroids – prednisone/prednisolone – which is considered a palliative treatment, aimed primarily at improving symptoms; steroids are not curative. Some ferrets are determined to be good candidates for chemotherapy. If specific tumors are causing problems due to their size, surgery may sometimes be helpful to relieve symptoms and reduce complications from that tumor. Radiation may be effective, but is not commonly offered.