Insulinoma In Ferrets

Its Cause, Diagnosis & Treatment

enlarge Why did my ferret develop this problem ?

Ron Hines DVM PhD

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What Is Insulinoma And How Does It Affect My Ferret?

Tumors of the pancreas are more common in ferrets than in any of our other pets. Ferrets over the age of five are the ones most susceptible to these tumors. They are visible as a single nodule or lump within the pancreas or as many small nodules. The arrows in the photo point to two of them.

Your ferret’s pancreas has two functions – the same ones as your pancreas. It supplies some of the enzymes you need to digest food and it supplies the hormone, insulin that regulates your blood sugar level. The portions that malfunction in insulinoma are the ones that produce insulin. They are called the islets.

The groups of cells in the islets that produce insulin are called beta cells. When these cells go out of control, they produce more insulin than your ferret’s body needs or wants. These abnormal beta cells multiply out-of-control to form raised lumps or nodules in your ferret’s pancreas.

Most ferret owners know about insulin because the lack of it, diabetes, is so common in people. In ferret insulinoma, exactly the opposite occurs – instead of not enough insulin, there is too much insulin. This causes blood sugar levels to drop too low (hypoglycemia).

Understanding the effects of insulinomas on your ferret, requires understanding how glucose is burned for energy in the cells of your ferret’s body. All cells run on glucose. In order for glucose to enter cells from the blood stream, insulin is required. When blood sugar level in the blood declines, insulin is released. Insulin alows the blood sugar to enter body cells by fitting like a key into receptors located on the cell's surface.

What Symptoms Would I See If My Ferret Had Insulinoma?

In the early stages of this disease, the signs are not specific and they are easy to overlook. Periodically, your ferret may look like it is preoccupied or uncharacteristically inactive and deep in thought. Healthy ferrets rarely sit still unless they are asleep. We think this is an early sign of low blood sugar. The Inability to think clearly is one of the first signs of hypoglycemia in people and it may be that something similar happens in ferrets too.

As the pancreas islets become more and more active, these troubling signs become worse. The ferrets become much less active than they should be. They loose their appetite and loose weight. They may vomit or drool and seem uncomfortable about their mouth. With time, it is very common for them to drag their rear legs (there are many other conditions besides insulinoma that also cause rear leg weakness). In advanced cases of insulinoma, the ferret’s blood sugar drops so low that the pet develops twitching and seizures. Left untreated, it will eventually fall into a coma and die.

It is often about the time the ferret has trouble walking that it first brought to a veterinarian. Ferrets age more rapidly than dogs or cats. They are also very prone to having glands, other than the pancreas, go out of whack. So by the time a veterinarian is brought into the picture, your ferret may have several health problems – particularly if it is over 7 years old. These common multiple problems include adrenal gland tumors as well lymphoma, heart and kidney disease.

How Will My Veterinarian Decide If Insulinomas Are The Cause Of My Ferret’s Problem?

The most direct test is to measure your ferrets fasting blood glucose level. That means, the blood must be obtained from your pet 4 + hours after its last meal. There are differences of opinion as to what the normal fasting blood sugar level of ferrets should be. Normal ferrets have a fasting blood glucose level of between 80-120mg/dl. Anything under 60-70 is very likely evidence that the pet has insulinomas. Anything under 85 is suspicious enough to run the test again. Fasting must be done with care and under close veterinary supervision because these pets are frail.

Once abnormally low blood glucose has been documented, your veterinarian will likely order several additional tests. They are included in what is called a blood chemistry panel. The first group of tests is to check the pet’s other organs. These tests are run because, occasionally, liver disease will lower blood glucose level and it is also rare for a ferret to develop insulinomas without having other organ problems as well. The other screening tests are to rule out a severe infection that might also account for low blood glucose.

Depending on the preferences and practice style of your veterinarian, they may also suggest x-rays to evaluate the pet’s heart, a urine examination to evaluate the pet’s kidneys and an ultrasound examination to screen for evidence of cancers. These other tests are a good idea if you or your veterinarian is contemplating a surgical option to deal with the insulinomas. They are less urgent if you are not.

What Treatment Options Are Available For My Ferret?

Insulinomas are a poorly understood condition in ferrets. It is obvious what is going on – the pet is producing too much insulin. But it is much less obvious what the underlying cause is that drives the ferret’s pancreases to over-produce. When we do not understand the cause of a disease, the solution is unclear as well. Until veterinarians figure out what false-signals are telling the pet’s pancreas to over-work, all we can do is deal with the symptoms – surgically, medically and nutritionally. It is a bit like slowing a speeding car by changing to smaller tires.
For now, there is no absolute or permanent cure for insulinomas. But one or a combination of treatments can often extend your pet’s life for as much as 2-3 years.


I suggest that your veterinarian evaluate your ferret’s current health. But I suggest that you decide what course of treatment is best for you and your pet. Here are the four things you must consider:

1) Can my family financially afford costly, extended treatment for my pet? For most people, there is no getting around asking this question. It is a fact of life you shouldn’t be ashamed of.

2) How many other concurrent diseases does my ferret have. It is rare for a ferret to develop pancreatic insulinomas before serious changes have developed in its other body system. That is why the additional tests are important.

3) How long has this problem been going on and how advanced is the disease. Pets respond best when treatment is begun early.

4) If I choose a surgical option, how likely is my ferret to survive surgery? Does it have heart, liver, adrenal or kidney problems that make it a poor surgical risk?

5) How old is my ferret? Unfortunately, the average life span of a pet ferret is about 8 years and many are not destined to live that long. Before you subject the pet you love to surgery, consider if it is really a kind thing to do.

If You Decide to have Your Ferret Treated With Surgery:

Most veterinarians have found that ferrets with insulinomas respond best to surgical, rather than medical treatment. Surgery will not cure your ferret entirely. But it should give the pet a reprieve from the problems of insulin over-production.

You veterinarian – or one you are referred to – can remove the visible nodules of over-producing tissue from your pet’s pancreas. At the same time, enough normal-appearing pancreatic tissue can be removed to bring the pet’s insulin production close to normal. Unfortunately, deciding the best amount of tissue to remove is very difficult. Too little, and the problem will not be solved. Too much and the pancreas can no longer do its job. Many of the decisions can only be made by careful inspection during surgery. That is why it is so important to use a veterinary surgeon that performs and follows up on many similar insulinoma cases. It is also quite common for other health problems to be discovered during this surgery. Some of these can be corrected at the same time and some cannot. You and your veterinarian need to discuss what you want done if these concurrent problems are discovered during surgery and how they might affect the outcome and cost of the procedure.

Is Surgery Always Successful?

No, success rates vary between surgeons. In general, about half the pets will do well for 2-4 additional years, when their long-term diet after surgery is controlled and they are given medications as needed.

What can I Expect after Surgery?

Most ferrets recover well from surgery. They are usually up and about quite quickly and their blood sugar value usually rises almost immediately. Check its surgical incision frequently to be sure it remains well closed and keep it from burrowing into sheets and bedding so you can closely monitor its condition. Be sure it is eating regularly, pooping and urinating.

An occasional ferret will develop abnormally high post-surgical blood sugar levels but these usually return to normal by themselves. A few others go on to develop diabetes when too much pancreatic tissue had to be removed.
However, it is not uncommon for blood sugar levels to begin to dip again in your ferret in 6-9 months. These ferrets will need their treatment continued medically. A second (or third) surgery is an option – but one I do not often advise.
The best way to monitor your ferret’s long term post-surgical pancreatic health or its health during medical treatment is with periodic blood sugar testing. This is something you can – and should – do at home.

What If I Decide To Have My Ferret Treated With Medicine?

Depending on the answers to my 5 questions, you may decide to treat your ferret medically, rather than surgically.
Low blood glucose (hypoglycemia) is your ferret’s problem, and medicines can raise it - for a while.

There are several medications that help ferrets with insulinoma:

Prednisone

Prednisone (or prednisolone) are steroids (corticosteroids) that often raise blood glucose levels. They do this through their affects on the liver. They are inexpensive. Corticosteroids have a number of undesirable side effects. But these side effects tend to be less of a problem in ferrets than in humans or dogs. It is not a very bitter drug, so it can often be given in a small bit of pungent food or in its pediatric liquid form. The correct dose varies between animals and needs to be tailored to your ferret by monitoring its blood glucose level.

Diazoxide (Proglycem®)

The oral form of this drug is used to treat hypoglycemia in humans. When it is given by injection in humans, it is used to control high blood pressure. It is a useful drug in ferrets when prednisone alone will no longer keep the pet’s blood sugar level high enough. It is usually given twice a day. Vomiting, poor appetite, diarrhea and listlessness are occasionally caused by this drug. Since ferrets with insulinoma must never go without eating, these can be very serious side effects. The medication has other side effects, so periodic blood testing of the pet is a wise choice when they are receiving diazoxide.

Doxorubicin and octreotide are two other medications that have been tried with mixed results.

Will It Be Important What My Ferret Eats?

Yes, It will be very important regardless what form of therapy you and your veterinarian choose. Ferrets with insulinoma need to be fed a diet that contains little or no grain, carbohydrate, starch or vegetable ingredients. Their food consumption needs to be closely watched because ferrets with insulinoma must eat frequently.

I do not know of any scientific data that shows that feeding a diet raw is in any way superior to feeding one that has been cooked. However, we do know that the grain products and sugars in many ferret diets and treats are not a normal part of a ferret’s natural diet. Ferret-like animals (mustella) thrive best when feed a diets containing primarily fats and protein. They were not designed to process or metabolize carbohydrates well and we know that carbohydrate levels play an important role in pancreatic health in all animals. They were also not designed to consume large amounts of fiber.

So no more raisins or sweets. Substitute liver, chicken hearts and other organ meats as rewards and treats.

What Are Some Steps I Can Take To Prevent Insulinoma?

Long before ferrets become ill with insulinoma, they will have abnormalities in their blood sugar level. So having their fasting blood sugar level determined yearly after they reach the age of 3 - 4 is a good idea.

Insulinoma is primarily a metabolic disease not a cancerous disease. It occurs because of the way the ferret’s body utilizes the nutrients in its diet to maintain its body. The most important step you can take to try to prevent this condition is to feed your pet a high quality, meat/poultry-based diet with as few additional plant ingredients as possible. Ferrets are very little animals. So even a few high-carbohydrate snacks and treats are significant.

When you purchase a processed ferret diet, a lot of decisions have gone into its manufacture that do not concern ferret health. One is the binding of ingredients together to form pellets. Carbohydrates aid in this. The other is the availability and cost of ingredients. Products labeled animal byproduct, digest or meal are not what you might think they would be (ref article). Do not feed diets containing these things to your pet.

The intestinal tracts of ferrets are relatively short. They will do better if allowed to munch their food throughout the day – rather than being fed at specific times.
Feeding your ferret “whole prey” is messy, gruesome business. Rodents you obtain that are bred locally often carry diseases much worse than insulinoma that can be a threat to both you and your ferret. That is why I do not suggest it.

Dealing With The Seizures of Hypoglycemia

Many ferrets with insulinoma never experience a seizure. But if yours does, take it to a veterinarian immediately. If at all possible, take it to a veterinarian experienced in treating ferrets – their blood vessels are hard to locate and their small size makes them easy to over or under-dose.

If there is a delay in reaching the veterinary hospital, give the ferret a dextrose (glucose) – containing product orally. Ferrets that are in the seizures of hypoglycemia can not swallow well. To prevent them from inhaling the sugar, just wipe their mouth with diluted Karo Syrup or Insta-Glucose gel. Do it with a Q-tip so you are not bitten.