Diabetes Mellitus

a common endocrine (hormonal) disease that affects both dogs and cats

What is it?
Diabetes Mellitus is a common endocrine (hormonal) disease that affects both dogs and cats. It occurs more commonly in middle aged to older animals. Female dogs are more likely than male dogs to get diabetes, while male cats are more prone than female cats. Dog breeds that are more at risk include Beagles, Cairn Terriers, Dachshunds, Miniature Pinschers, Miniature Schnauzers, Poodles and Pulis. No specific cat breed is more predisposed than another.

Diabetes can be of two types – insulin dependent and non-insulin dependent. The former is more common. Insulin dependent diabetes means the pancreas is not producing adequate levels of insulin, while non-insulin dependent diabetes is when there is resistance to the insulin being produced so that it cannot exert its effects.

What causes it?
Insulin is a hormone produced by the pancreas in response to increasing levels of glucose (sugar) in the blood. The sugar comes from the meals that the animal eats. Insulin tells cells to absorb the glucose from the blood and use it for energy. In a diabetic animal this insulin is not made (or is not detected) and the cells cannot absorb glucose and the levels of glucose remain high in the blood. This excess glucose will spill over into the urine and will pull more water in the urine. This is why diabetics have glucose in their urine and it is why they urinate more frequently.

What are the symptoms?
An animal that is diabetic will urinate and drink more frequently, often eat more, have weight loss, may have cataracts develop, and may be weak in the hind end. If they are severe enough, they may vomit, be inappetant, be very weak, may be breathing very fast or slow, and may have foul breath. These later cases are emergencies and need to be seen immediately.

How is it diagnosed?
Diabetes is diagnosed by detecting elevated glucose levels in the blood and urine. A full blood chemistry, CBC, and urinalysis should be done to rule out concurrent disease that may complicate and alter the animal’s response to treatment.

How is it treated?
Treatment for diabetes involves correcting any electrolyte abnormalities and dehydration. To correct the diabetes, insulin injections need to be given under the skin. This is usually done twice daily and the injections are given after a meal. It is important that the right dose is given, that the insulin is mixed properly, that the injection sites are changed, and that the animal eats first. If these things are not done, the insulin may not have an effect, or the glucose might be dropped too low. Dropping the insulin too low can be life threatening. The animals diet is also changed to a high fiber diet to slow absorption of glucose and to prevent large fluctuations in blood glucose levels.

What is the prognosis?
Prognosis for a well-regulated diabetic is good. They do, however, require lifelong treatment. For those animals that are not well regulated, testing should be done to check for complicating diseases. Examples of some of these diseases include pancreatitis, chronic infections, other endocrine diseases (hypoadrenocorticism, hyperadrenocorticism, hyperthyroidism, hypothyroidism), neoplasia (or cancer), etc.

Cataracts will develop in all pets afflicted with diabetes. In some cases, this may be a very rapid onset causing acute blindness. In others, cataract formation may be slowly progressive. Proper control of the diabetes will aid in slowing the onset of cataracts.