What are they?
Insulinomas are a tumor of the pancreas, an organ responsible for producing several different hormones, as well as digestive enzymes. Specifically, they are an overgrowth of the cells that secrete insulin. Insulin is a molecule that helps to keep blood sugar low. Normally, it is released after an animal eats, and has a variety of effects, all of which are geared towards storing glucose. These include telling cells to let more glucose in from the bloodstream, preventing the production of new glucose, and encouraging the storage of glucose as a molecule called glycogen.
What do they do?
If a ferret has an insulinoma, the tumor secretes insulin all the time, instead of just after meals. With too much insulin circulating in the blood, blood sugar levels can drop dangerously low.
This is a condition known as hypoglycemia.
What kind of signs would I see if my ferret had an insulinoma?
The most common early symptoms of an insulinoma are weakness and lethargy. Your ferret may stare blankly into space, seem dull and uninterested in his or her surroundings, and be less interested in playing. Ferrets may also paw at their mouths.
Other symptoms include difficulty walking, drooling, and collapse. Occasionally, ferrets with severe hypoglycemia may have seizures, which can look like uncontrollable twitching while laying down. If the hypoglycemia continues, it can cause coma or death.
How are insulinomas diagnosed?
If your veterinarian suspects that your ferret has an insulinoma, he or she will most likely test your ferret’s blood glucose level. To be completely accurate, this may involve withholding food for a few hours before testing. Diagnosis may also include testing the insulin level. A high insulin level with a low blood glucose is confirmatory for an insulinoma.
How are insulinomas treated?
There are essentially two pathways to managing an insulinoma: surgical or medical. Typically, surgery results in longer survival times, but it can have risks as well. You should discuss with your veterinarian which option is right for you and your pet.
Surgical management involves removing part of the pancreas. This may involve just removing the tumor (a nodulectomy) or removing an entire section of the organ (partial pancreatectomy). With some tumors, this can resolve the symptoms for a period of time.
However, sometimes there are tumor cells spread out into the pancreas, and removing the main tumor does not prevent future hypoglycemia. If it is successful, your ferret may have a period of time with no symptoms.
Medical therapy involves drugs used to keep blood glucose at a safe level. Typically, this includes the steroid prednisone, which encourages glucose production and decreases glucose uptake by cells. It also often includes diazoxide, which prevent the release of insulin from the pancreas. Octreotide is another less common option which helps to inhibit insulin release. Finally, chemotherapy with the drug doxorubicin can be used to kill the tumor cells. Ask your veterinarian about which medications they think are best for your ferret.
Dietary management is an important part of medical therapy. Ferrets with insulinomas should eat a high protein, high fat, low carbohydrate diet. Avoid sugary treats, as these may stimulate more insulin release from the tumor. Your ferret should have access to food at all times, to avoid surges of insulin release after a big meal. Your veterinarian may also send home a glucose gel to give to your ferret if he or she becomes hypoglycemic.
What should I expect with treatment?
Although insulinomas are a type of cancer, they do not commonly spread to other organs. However, even with treatment or removal, they almost always recur. Treatment is based on slowing or temporarily stopping the symptoms, but this is a progressive disease. With a partial pancreatectomy, the average ferret can live almost two years. Ferrets that are medically managed typically live for about six months. Regardless of what type of treatment you choose to pursue, the most important goal is improving your ferret’s quality of life.
Girling, S. J. (2011). Endocrine Disease in the Ferret. British Small Animal Veterinary Congress 2011. Retrieved from http://www.vin.com/doc/?id=4823158
Murray, J. (2012). Ferret Endocrinology: Hyperadrenocorticism, Insulinoma, and Diabetes. Association of Avian Veterinarians Annual Conference 2012. Retrieved from http://www.vin.com/doc/?id=6347752
Rhody, J. L. (n.d.). Ferret Abdominal Diseases (Foam Slippers and Abdominal Zippers). In Western Veterinary Conference 2012. Retrieved from http://www.vin.com/doc/?id=5603629