Common Conditions in the Older Ferret

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Heidi L. Hoefer, DVM, Dip. ABVP

Island Exotic Veterinary Care
Huntington, New York

The average lifespan of the pet ferret is 6-8 years, making a 3 year old ferret "middle-aged", and a 5 year old an "older" ferret. While all ferrets should be checked annually for vaccinations, there are certain "old-age" conditions that are common, making biannual visits important as the ferret ages. This article covers some of the most common diseases seen in older ferrets.

Dental Disease

Dental tartar, gingivitis, and periodontal disease are common as a ferret ages. Tartar formation starts in the young ferret and can progress, even on a hard, dry diet. The biting and gnawing habits of some ferrets results in broken and discolored canine teeth. Tooth root abscesses are uncommon but can occur at any age.

Dental disease is often an incidental finding during physical exam. Dental extractions and scaling can be performed under anesthesia. Tooth brushes ("finger brushes") and paste made for cats can be used in some ferrets.
Adrenal Cortical Disease (see other article on website)
Adrenal disease is most common in ferrets over 2 years of age but can also sometimes be seen in younger ferrets. This is a tumor of the adrenal gland that results in overproduction of steroid sex hormones like testosterone, estrogen, and progesterone. Several hormones may be involved. This is not the typical Cushing's disease seen in dogs and people.

Symptoms include varying degrees of fur thinning and fur loss, itchy skin, , and in some spayed females, a swollen vulva may result.

Diagnosis is based on clinical appearance of fur loss, palpation of adrenal glands, sonogram, and ultimately, adrenal biopsy taken at surgery. A blood test can be taken to check for abnormally high hormone levels.
Treatment involves surgical removal of the affected gland. In a small number of cases, both glands may be affected. Removal of one gland and biopsy of the second is recommended in these cases. Metastasis is rare; surgery is usually curative. Biopsy of the affected adrenal gland usually shows a benign tumor called an adenoma. Medical therapy using leuprolide (Lupron) can be used in some ferrets that cannot have surgery performed.

Insulinoma (click here to see article on this topic)

Pancreatic beta cell tumors (insulinomas) are very common in ferrets over 4 years of age. There is an overproduction of insulin by the pancreas resulting in hypoglycemia. Clinical signs are attributable to hypoglycemic episodes: hindlimb weakness, loss of balance, hypersalivation, increased amounts of sleeping, glazed eyes or stuporous appearance. Seizures are usually seen only in advanced cases. Onset is often insidious and many owners miss the early signs of the disease.

Diagnosis is based on symptoms, and persistently low blood sugar levels (<60mg/dl). Insulin blood levels are not reliable; i.e., values can be normal in an affected ferret. XRAY's and sonograms are non-diagnostic but can be useful screening tests in older ferrets.

Treatment can be medical or surgical or a combination of both. Medical therapy is designed to increase the blood glucose concentration. Prednisone (Pediapred® given every 12 hours) is used to increase blood sugar levels and is the first line of treatment. Diazoxide (Proglycem®) is added if and when hypoglycemic episodes return. Surgical treatment involves excising individual nodules or part of the pancreas. Most insulinomas have spread (metastasized) to other parts of the pancreas by the time of diagnosis making treatment not curative. Fortunately, this is a slow process and once diagnosed, ferrets can live 6 - 24 months with appropriate therapy. Prognosis varies and depends on the age, degree of metastasis, and chosen therapy (medical or surgical).

Heart Disease

Congestive (dilated) cardiomyopathy is the most common heart disorder in older ferrets. Hypertrophic cardiomyopathy and valve conditions also occur in the ferret.

Symptoms vary: some ferrets have no signs at all and others have trouble breathing and are weak. Weakness and lethargy are common and should not be mistaken for an insulinoma (which could look very similar before tests are conducted). Diagnosis is made with a stethoscope (abnormal beats and murmurs are heard), XRAY's, EKG's, and echocardiograms. Definitive diagnosis can only be made with echocardiography.

Treatment of heart disease follows the same protocol used in other animals: diuretics like Lasix®; blood pressure drugs like enalapril, and contractility drugs like digoxin are often used. Long term prognosis for ferrets with cardiomyopathy is guarded. With early diagnosis and proper therapy, many of these ferrets can have a good quality of life for many months.
Just like our dogs and cats, ferrets of any age are susceptible to heartworm disease if housed outdoors in heartworm endemic areas. Although uncommon, this infection can result in severe cardiac disease in the ferret. Even a very low parasite burden (one or two worms) can have serious consequences. Prevention is best achieved by use of monthly drugs to prevent maturation of the parasite.

Lymphosarcoma

Two different age groups are represented: young ferrets 10 mos - 1.5 years and older ferrets > 3 years. In older ferrets, lymphoma often follows a more chronic course associated with enlarged lymph nodes, although any orhgan can be involved. Diagnosis is based on biopsy. Prognosis depends on extent of disease at the time of diagnosis and response to treatment. Treatment varies between clinicians and hospitals; several chemotherapy protocols have been published.

Skin tumors

Mast cell tumors are common in the skin of older ferrets. Typically these are small, round slightly raised lesions that may bleed and scab up often. Although these tumors are benign in ferrets, surgical excision and biopsy is recommended and considered curative. There are several other 'lumps and bumps" that can be seen in the skin of ferrets and because it is impossible to tell offhand which ones are serious, they should all be evaluated by a ferret vet.