Ferrets are high-energy critters that spend hours each day playing and looking for ways to escape. As a result, it can be extremely alarming if your ferret suddenly lacks energy to play. This lethargy is commonly caused by a tumor of the pancreas called insulinoma.
The pancreas is an organ in the body that has two main functions: the production of enzymes that aid in the digestion of food, and the production of hormones such as insulin, which regulate metabolic processes within the body. Insulin is produced by beta cells in the pancreas, found in clusters known as the Islets of Langerhans.
When blood glucose (sugar) levels are increased after a meal, the beta cells release insulin into circulation. The insulin plays an important role in helping cells take up glucose, which is converted to energy that will later be used by the cell.
Insulin also promotes the storage of glucose in the liver in the form of a compound known as glycogen. Furthermore, insulin plays a role in the production of new proteins within cells, the absorption of amino acids from the gastrointestinal tract, the maintenance of potassium levels in circulation that is critical for cardiac function, and the storage and release of fat from fat cells. As a result, it goes without saying that insulin is an extremely important hormone in the body and any long-term increase or decrease in the amount of insulin can drastically alter body functions.
Domestic ferrets seem to have a genetic predisposition to developing tumors of the cells that produce insulin, resulting in a variety of classical clinical signs that will be discussed later. Unfortunately, ferrets are often considered to be little “tumor factories”, as cancer is likely the most common reason for euthanasia in older ferrets. The most common type of cancer is insulinoma, followed by adrenal disease and lymphoma. Insulinomas can occur in ferrets at any age, but most often develop in animals four years of age or older. Both males and females seem to be affected equally.
Early symptoms of the disease can be subtle and may go unnoticed for a period of time. Clinical signs are related to the decrease in blood glucose, a consequence of excessive insulin in circulation. You may only notice your ferret sleeping more than usual or not showing as much enthusiasm for play time. Weight loss can gradually occur as food intake decreases and the body’s fat stores are being used up. Your ferret may exhibit “episodes” of lethargy in the “flat ferret” posture with eyes gazed over. More obvious symptoms include excess salivation and pawing at the mouth as if there was a foreign object stuck there; this can be attributed to nausea caused by the decrease in blood. Finally, in severe cases, your ferret may experience seizures if glucose levels are extremely low.
Diagnosis of insulinoma may require consecutive blood tests to check glucose and insulin levels. Due to the small size of their veins, if your ferret is of the squirmy variety, he/she may need to be mildly sedated or even anesthetized for blood collection. Only a small amount of blood is needed and results from the laboratory are generally quick. An ultrasound is often utilized to check for visible tumors on the pancreas, which can often be quite large in more advanced cases. One of the drawbacks of insulinoma, however, is that small tumors that may not even be visible to the naked eye, can produce large amounts of insulin. Furthermore, there is almost always more than one tumor present. Ultrasound is not always successful in imaging the tumors, and the ultimate means of diagnosis is to open up the abdomen under anesthesia to manually look for tumors.
Symptoms of insulinoma can be an upsetting experience for a ferret owner that has not experienced this disease before. Temporary control of clinical signs, however, can be managed at home until veterinary care can be administered. If your ferret is experiencing an “episode”, you can temporarily increase blood glucose levels by rubbing (not pouring) a small amount of corn syrup or honey on the gums. Be careful, however, not to get bitten. If there is a risk, you can try using a cotton swab for administration. Contact your veterinarian for help and further treatment if clinical signs persist. Ferrets experiencing seizures that cannot be managed with honey require immediate veterinary care.
A good policy is to have a good quality, high protein food available at all times. Have food available in all areas of the cage so that your ferret can always have quick access to it. Often, it is useful to have wet food available as well, if your ferret will eat it, as some ferrets are more keen on the softer food. Sugary and/or carbohydrate-rich treats, including fruits and raisins should not be given.
There are a variety of treatments available, both medical and surgical. The medical therapy of choice is often the steroid prednisone. It acts by maintaining blood glucose levels by a number of methods. For example, it increases glucose released from the liver and inhibits some tissues from taking up glucose. Several other drugs are also available, but most are still in the preliminary testing stages. It should be noted, however, that the use of medical therapy only controls the symptoms of low blood glucose, and does not stop the progression or cure insulinoma. The average survival time for ferrets treated with medical therapy alone has been reported as six to nine months.
Ultimately, the best way to manage insulinoma is surgery. Often this is performed by a ferret-experienced veterinarian as these critters are slightly different from cats and dogs. Your veterinarian will assess your ferret’s ability to handle anesthesia by means of a physical exam and blood tests. If your ferret is a candidate, your veterinarian can explore the abdomen and look for obvious nodules on the pancreas. In most cases, any visible nodules can be removed with few complications. Unfortunately, surgery should not be viewed as a cure. As mentioned before, ferrets are little “tumor factories” and although visible nodules can be removed, there may be many other microscopic ones waiting to grow. It is quite common for clinical signs to reoccur because of new tumors several months after surgery. Survival time with surgery is estimated to be between one and three years.
With diligent home care and appropriate veterinary care, a diagnosis of insulinoma can mean many more good times with your ferret. Although the disease is unpredictable at times and often reoccur when you least expect it, recent advances in medical and surgical therapies can ensure that your ferret’s health can be maintained for a longer period of time.
By Beverly Wong – Pets.ca writer