Diabetes mellitus in dogs is the same disease seen in humans, where it is referred to as Type I diabetes. The immune system destroys the insulin-producing capacity of the pancreas impacting the dog’s ability to control blood sugar levels. Affected dogs drink water and urinate excessively, and tend to lose weight, sometimes in spite of increased appetite. They may be exercise intolerant and prone to infection and might develop secondary cataracts. Age of onset is usually middle-aged and older. It can be secondary to obesity or long-term steroid use. Diabetic dogs can develop ketoacidosis, a life-threatening condition.
Diagnosis is made by determining levels of sugar in the blood and urine. Treatment is once- or twice-daily insulin injections.
Primary diabetes mellitus is a type of autoimmune disease. Autoimmune diseases are genetically predisposed; if a dog has the disease, it has the genes. Dogs affected with primary disease should not be bred. Their near relatives should not be bred to mates with a family history of any autoimmune disease.