I lived with two ferrets back in my vet school days — a little female who liked nothing better than to hide under the couch and surprise people by nipping their ankles when they sat down and a big sweet boy (with the politically incorrect name of Louis Ferretkhan) who loved to cuddle. They weren’t mine, but they provided me with hours of entertainment nonetheless.

Unfortunately, my experiences with ferrets as a veterinarian have not been so positive. They are prone to a number of serious health problems, including insulinomas.

Insulinomas develop when beta cells in the pancreas become cancerous, which leads to an overproduction of insulin. Insulin is the hormone that transports glucose (i.e., sugar) from the bloodstream into cells, where it can be used for energy.

When clients hear the word "insulin," their thoughts often turn to the disease diabetes mellitus, but insulinomas actually create the opposite problem: hypoglycemia (low blood sugar) rather than hyperglycemia (high blood sugar). In other words:

  • Insulinoma → too much insulin → low blood sugar
  • Diabetes mellitus → not enough insulin → high blood sugar

Normally, a ferret’s blood sugar level should be well over 70 mg/dl. With insulinomas, the number can be much lower, and ferrets typically develop some combination of the following:

  • Lethargy
  • Weakness
  • Stupor
  • Drooling
  • Weight loss
  • Weak back legs
  • Vomiting
  • Pawing at the face, especially around the mouth
  • Poor coordination
  • Twitching, tremors, and seizures

Veterinarians can usually diagnose ferrets with insulinomas based on their clinical signs and a finding of low blood sugar on a laboratory test. A recent meal will sometimes cause blood sugar levels to temporarily climb into the normal range, so your veterinarian may want to withhold food for a few hours, but this should be done in the clinic so the ferret can be closely monitored and treated appropriately should problems arise.

Surgically removing insulinomas is possible. The procedure rarely cures the disease, however, but it will slow its progression. Since the tumors are often tiny, the chances of removing all of them are low.

Insulinomas can also be treated medically, and this is usually necessary even after surgery has been performed. Corticosteroids (e.g., prednisone) increase blood sugar levels, and the drug diazoxide can inhibit the release of insulin from the pancreas. Dietary modifications are also important. The goal is to feed a diet that helps prevent wild swings in blood sugar levels. Foods that are high in protein and fat and low in carbohydrates are best and should be offered frequently. Foods and treats that are high in carbohydrates should be avoided as they can cause blood sugar levels to spike with a dangerous trough to follow. But, always keep corn syrup or honey on hand for emergencies. When a ferret shows signs of low blood sugar, rub the sugary solution on its gums and get to your veterinarian ASAP.

Unfortunately, most ferrets with insulinomas eventually must be euthanized because they are no longer responding well to treatment. However, with appropriate therapy many can enjoy good quality of life for quite a while, using this time to nip ankles with impunity and/or cuddle up for lots of good snuggles.

Dr. Jennifer Coates

Image: Einar Muoni / via Shutterstock