INSULINOMA (HYPOGLYCEMIA)

Hypoglycemia is low blood sugar, and in ferrets this is caused by pancreatic nodules called insulinomas or islet cell tumors. While these tumors are usually benign, they produce large amounts of insulin, which lowers blood sugar (glucose) levels. This is the opposite of the situation encountered with diabetes, where low insulin levels lead to high blood glucose levels. Hypoglycemia is a common disease in adult ferrets of both sexes.

Symptoms of hypoglycemia can be very subtle in the beginning. As the disease develops over many months, symptoms become increasing severe and ultimately fatal. Initially episodes of weakness or disorientation arise, then quickly pass after a matter of several seconds or minutes. Ferrets may stand still, staring blankly during a hypoglycemic episode, or may temporarily drag the rear legs while moving about. As the disease progresses and the tumors grow, the ferret may salivate and make chewing motions. Rubbing or pawing at the face is also frequently noted during a hypoglycemic attack. Episodes become more frequent and more severe, ultimately leading to collapse, seizures or coma.

Diagnosis of insulinoma in the ferret can usually be made, or strongly suggested, on the basis of fasting blood glucose levels. A blood test is taken following a 4-6 hour fast, with levels below 70mg/dl strongly suggestive of insulinoma. Assays of blood insulin taken at the same time as the blood glucose test can be helpful in diagnosing insulinomas in ferrets whose glucose levels alone are equivocal.

Treatment recommendations for insulinomas may vary, but I believe insulinomas initially are best treated by surgical exploration and removal if possible. This allows a confirmation of the diagnosis, and it provides the veterinarian with an opportunity to remove any obvious pancreatic masses. Insulinomas may occur singly or as groups of small nodules. Unfortunately, these nodules may be so small and diffuse throughout the pancreas that they are not apparent to the surgeon. In this case, some veterinarians will perform a partial pancreatectomy in an attempt to remove some of the insulin-producing cells.

Insulinomas are frequently a recurring problem. It is important for ferret owners to realize this, as blood glucose levels often start to fall within a few months even following successful surgery. Frothier control of blood sugar levels can be achieved by frequent small meals which are high in protein and complex carbohydrates, but low in simple sugars. Because of its ability to raise blood sugar levels, prednisone or related corticosteroids are widely used in ferrets where surgery was declined or was unsuccessful at normalizing blood glucose. Another medication which can be useful is diazoxide (Proglycem), although it is expensive and response varies. Insulinoma in ferrets is best seen as a disease which can be managed but seldom cured. With carefully supervised treatment consisting of surgery, diet control, and medications an affected ferret's lifespan can be increased by up to three years.


If you have any questions or comments about the information above, feel free to send a message to Dr. Suzanne Lee, D.V.M. at SLeeDVM@aol.com.

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