Ferrets - Tumours

As with any animal ferrets can suffer from a wide range of tumours from benign cancers of the skin to aggressive malignant tumours of internal organs. It does appear that a large number of ferrets are affected by tumours of the lymphoid system and the pancreas. Here we will discuss these two tumours only, although tumours of the skin are discussed with dermatological disease (Ferrets – Skin Diseases).

Lymphoma

Lymphoma, a tumour of the lymphoid (immune) system can affect ferrets of all ages and in these cases is a severe disease with weight loss, anorexia and lethargy. Respiratory problems and coughing may occur as may hind limb weakness. This diversity of signs can make diagnosis difficult but enlargement of the lymph glands makes one suspicious. Biopsy will confirm. Sometimes there is a high lymphocyte count in the blood. There is no cure for lymphoma, but chemotherapy regimes may provide a very good quality of life for a period (sometimes a year or more).

Insulinoma

Tumours of the pancreas involving the beta cells which produce insulin are surprisingly common in ferrets. Since insulin reduces blood sugar, an increase in this hormone as produced by an insulinoma results in dangerously low levels of glucose in the blood with the risk of the ferret lapsing into a hypoglycaemic coma. In fact the results of these low levels of blood glucose are manifest on the brain and the adrenal gland. Neurological signs include dullness and confusion but end in seizures and coma. Some ferrets will hypersalivate and paw at their mouths. The adrenal gland reacts to precipitous reductions in blood glucose by producing adrenaline and so the signs of this include a rapid heart rate, tremors and irritability. On the other hand some ferrets with tumours of the pancreas show no obvious clinical signs.

So how are insulinomas diagnosed? A measure of blood insulin would seem the obvious test, but all too often ferrets with insulinomas have normal insulin levels at the time of sampling. The ratio of insulin to glucose is a more useful test, since if there is a high level of insulin in the face of a low glucose level, the diagnosis is definitively made. Persistent hypoglycaemia, suspicious signs, and response to glucose therapy will make the clinician suspicious enough to justify tests such as abdominal ultrasound and (more usually) exploratory surgery.

Hypoglycaemic attacks should be treated by rubbing honey or glucose syrup onto the gums, the only danger of this being a bite, especially if the ferret is having seizures. A veterinary surgeon attending such an emergency will give 50% dextrose intra-peritoneally or intra-venously after controlling fitting by anaesthetizing or sedating the ferret. 

Surgical treatment to remove the tumour is the optimal therapy and the largest reported series of cases to date demonstrated a mean survival time after surgery of around 500 days, which is relatively long given that these are generally middle-aged ferrets. For those that are not amenable to surgery, prednisolone and diazoxide have been used to control the disease.

Skin tumours

Rarely lymphoma may affect the skin. However, benign skin masses are common. These are usually mast cell tumours or basal cell tumours and excision is curative.