What is Insulinoma?

Insulinoma is an endocrine disease that occurs quite frequently in ferrets. Most ferrets are 5 or more years of age when the disease is diagnosed. To a certain degree, insulinoma is related to diabetes. Both conditions are caused by disease of the pancreas. In diabetes the pancreas produces little or no insulin, and as such blood sugar (glucose) levels are high.

With insulinoma, the situation is reversed. One or more small tumors on the pancreas produce too much insulin. This high level of insulin leads to a significant drop in glucose levels and several symptoms, including:

• Lethargy and weakness - While these signs are non-specific, they are by far and away the most common symptoms seen in ferrets with insulinoma. The weakness may wax and wane; however, as the disease progresses it will be more apparent and may occur 100% of the time.
  
  
• Pawing at the mouth and increased salivation - It is not known why ferrets do this, but it has been speculated that ferrets with insulinoma feel nauseous and paw at their mouth salivate as a response to the nausea.
  
  
• Vomiting - This symptom is not as common as the others mentioned above, but it can occur with insulinoma.
  
  
• Seizures (fits) - While seizures are not common with insulinoma, they do occur. Seizures are particularly likely to occur with severe insulinoma, or in those cases in which diagnosis and treatment by a qualified veterinarian is delayed.

If you notice any of these signs in your ferret, you should seek help from a qualified exotic pet veterinarian. If you suspect insulinoma, inform the staff at your veterinarian's office. They will likely ask that you bring the ferret to the clinic on an empty stomach (after a 2-3 hour fast). By doing so, appropriate blood tests can be performed at the time of your appointment and a diagnosis can be reached rapidly.

How is Insulinoma Treated?

Insulinoma may be treated medically or surgically. The decision to choose one over the other is made on the basis of the ferret's age, general health and ability to withstand surgery.

The aim of surgery is to remove the mass or masses within the pancreas. Your veterinarian may discover that your ferret has more than one mass, and that it is not possible to surgically remove all of them. Should this happen, any large mass and as many small masses as possible will be removed if your veterinarian believes it is safe to do so. In these instances the ferret will need to be managed medically (given medication) after surgery.

Medical management can be performed alone, or if surgical intervention fails to remove all of the insulin-secreting masses within the pancreas. Medical management usually consists of treating the affected ferret with a liquid medication known as prednisolone. The aim of this medication is to increase blood sugar levels and counteract the symptoms of insulinoma.

Medical therapy does not treat the pancreatic tumors that are responsible for the disease, but rather treats the symptoms. This is critical as low blood sugar can be fatal if not controlled. Many ferrets live several years on their medication.

Close follow up is required with your veterinarian to ensure the appropriate dose of medication is being given. Your veterinarian will wish to recheck blood sugar values fairly frequently until levels are stable. Your ferret should always be evaluated 2 to 3 hours after eating and taking the morning dose of medication. This check takes variability caused by food and medication out of the equation when your veterinarian evaluates your ferret's progress.

No matter what type of treatment is chosen, it is important to stop giving your ferret sugary treats and supplements. This may seem counterproductive since insulinoma causes disease by decreasing blood sugar. However, giving your ferret sugary treats causes the pancreas to secrete even more insulin and this can cause a sudden and severe drop in blood sugar.

With time, most ferrets require more prednisolone as the disease progresses. At a certain point the amount of medication may be difficult to administer. At this point, your vet may suggest adding another medicine known as diazoxide. This medication is quite expensive and is often reserved for cases where prednisolone is not working as well as it should.

In conclusion, insulinoma is caused by one or more tumors in the pancreas. These tumors secrete too much insulin and cause blood glucose levels to fall to dangerously low levels. The disease is common in older ferrets and diagnosis is relatively straightforward. The disease can be managed medically or surgically, but either option will require close cooperation with your exotic pet veterinarian and relatively frequent follow-up until the blood sugar levels are stable.