An insulinoma is a malignant tumor of the pancreas that secretes excessive amounts of insulin leading to hypoglycemia (low blood sugar concentration). Insulinomas usually occur in middle-aged to older dogs, usually eight to twelve years of age. They are very rare in cats and there is no apparent gender predilection.

Insulinomas can occur in any breed of dog with mixed breed dogs most commonly affected. Among purebred dogs, Irish setters, German shepherds, boxers, golden retrievers, poodles, and Labrador retrievers have a higher incidence. Medium to large-sized breeds of dogs are most commonly affected.

The excessive secretion of insulin by these tumors causes hypoglycemia and clinical symptoms of hypoglycemia.

What to Watch For

Seizures

Collapse

Fainting (also called syncope)

Generalized weakness

Hind limb weakness

Lethargy

Incoordination

Muscle tremors

Unusual behavior

Polyphagia or increased appetite

Exercise intolerance

Shaking

Trembling

Nervousness

Dilated pupils

Blindness