The pancreas is an organ located in the abdomen, close to the stomach and the liver. Its function is twofold: the regulation of blood sugar levels thanks to insulin secretion and the digestion of fats and proteins thanks to the secretion of specific enzymes.
Insulin is produced by pancreatic cells called β islets of Langerhans. When blood sugar is high, after a meal for example, insulin is secreted by these cells. This allows sugars to enter the cells of the body and subsequently be used as a source of energy. Sugars are the almost exclusive fuel for neurons and muscles during intense efforts.
Thanks to this mechanism, the level of sugars in the blood does not remain high. Indeed, a consistently high blood sugar level is toxic to many organs and leads to diabetes mellitus. On the other hand, when blood sugar is low, the pancreas does not secrete insulin in a healthy individual.
In the case of insulinoma, a tumor of β cells, the pancreas secretes too much insulin and causes persistent hypoglycemia.
Insulinoma is much more common in dogs than in cats. Large breed dogs are more commonly affected than small breed dogs. These are usually malignant tumors. In 50% of cases, at the time of diagnosis, metastases are already colonizing other organs.
Symptoms are associated with hypoglycemia and are mainly neurological. The animal shows weakness, uncoordinated movements, tremors, restlessness, epilepsy, weight loss. These symptoms are often intermittent and can be triggered by exertion or exercise, excitement or fasting. Some dogs are minimally symptomatic because they have adapted to prolonged hypoglycemia.
The diagnosis is based on the demonstration of a low glucose level associated with high insulin levels in the blood.
Medical imaging examinations such as ultrasound and/or abdominal CT scan make it possible to visualize the location of the insulinoma within the pancreas and to look for the presence of metastases.
Surgical removal of the insulinoma is the treatment of choice. When present, metastases can sometimes also be partially or completely removed surgically.
If surgery is not feasible, or if hypoglycaemia persists despite the operation, medical treatment may be considered. First, through the administration of many small meals to maintain stable blood sugar throughout the day. Then, certain drugs that have the effect of increasing blood glucose and decreasing the production and secretion of insulin by β cells can be used.
The prognosis depends on the stage of disease progression at the time of diagnosis and the type of treatment instituted. Overall, a better prognosis (median survival of 1.5 years) is observed in dogs treated by surgery with or without postoperative medical treatment, than in dogs treated medically only.
Dr Emilie Vangrinsven
Diplomate from European college of veterinary internal medicine | PhD U-Liège
Assistant at the Liege University in the university clinic for PETs | Author and co-author of numerous scientific publications
