An insulinoma is a malignant type of cancer that produces an excess quantity of the hormone, insulin. The excessive insulin secretion results in the increased uptake of glucose from the blood stream by muscle, fat and other tissues of the body as well as a reduced production of glucose by the liver. Both these contribute to a low blood sugar level, or as it is more correctly known, hypoglycaemia.

An insulinoma is also known as a pancreatic islet beta-cell cancer, B-cell tumour, Islet cell tumour and Insulin-producing pancreatic tumour.

Insulinomas are uncommon in dogs and rare in cats (there have only been 4 reported cases!). The Standard Poodle, Boxer, Fox Terrier, Irish Setter, German Shepherd, Golden Retriever and Collie appear to be more commonly affected than other breeds.

Males and females are affected at the same frequency.

Dogs aged 3-14 years of age have been affected but the average age is 10.5 years.

Dogs with an insulinoma can present with the following symptoms:

Animals with an insulinoma tend to show vague signs initially but as time passes these signs become more severe.

Fasting, excitement and exercise may increase the risk of hypoglycaemia and cause the symptoms to develop.

In the early stages when symptoms are mild, an insulinoma’s effects can be controlled medically. This is achieved by feeding 4-6 small meals a day. The diet should be high in protein, fat and complex carbohydrates and low in simple sugars.

If modifying the diet does not control the problem then cortisone can be used to stimulate an increase in the blood sugar.

Surgery can be of great benefit. Surgical removal of the cancer can improve survival time, improve quality of life and provide prolonged remission. Spread of the cancer from the pancreas to the liver can be expected in 40% of patients at the time of surgery.

Like any surgery there are always risks. These include the risks associated with anaesthesia and post-operative infection. Dogs with an insulinoma will require intravenous fluids with glucose added to it to ensure their blood glucose levels do not drop too low during the operation. The pancreas is a very sensitive organ and does not respond well to handling. In most cases the patient can be expected to develop some inflammation in the pancreas after the surgery. This is known as pancreatitis and is the most common problem encountered with any surgery involving the pancreas.

In both dogs and cats the chance of the cancer spreading is high. The average survival time in dogs is 16-19 months but this can be increased if surgery is successful in removing obvious cancers.