Diabetes mellitus is a disruption of the body's ability to use carbohydrates/sugars. Normally, certain cells in the pancreas produce the hormone insulin which regulates the uptake of sugars into cells throughout the body. In some forms of diabetes mellitus, the cells are dysfunctional and do not produce insulin, while in other forms insulin is produced but body tissues do not respond appropriately.
Genetics is only one of many factors that may be involved. In some dogs there seems to be a genetic predisposition to to the destruction by the immune system of the insulin-producing cells. In other dogs, less severe genetic-based changes in the cells may make the dog more susceptible to the development of diabetes mellitus - in association with another illness or obesity or exposure to certain drugs.
In keeshonds, diabetes mellitus is inherited as an autosomal recessive trait. The mode of inheritance has not been determined in other breeds.
In dogs with the most severe form of inherited diabetes mellitus, signs are usually apparent by 6 months of age. Pups drink and eat more than normal, and yet grow very slowly. They urinate frequently, and their stools are soft.
In other dogs, diabetes mellitus does not develop until middle age. The signs of uncomplicated diabetes are typical - increased eating, drinking, and urination, with weight loss - all of which are a result of increased levels of glucose in the blood and urine. Over the long term, this can lead to the development of cataracts, increased susceptibiIity to bacterial infections (especially of the urinary tract), liver disease, and pancreatitis. Eventually, untreated diabetic dogs will develop ketoacidosis, a very serious condition. Signs of ketoacidosis include depression, weakness, vomiting, and irregular breathing patterns.
The diagnosis is made based on the typical clinical signs - increased eating, drinking, and urination, with weight loss - together with persistently elevated levels of glucose in both the blood and the urine. Ketones may also be present in the urine. Your veterinarian will do a complete laboratory work-up, to see if there is any other condition that may be causing or contributing to, or occurring as a result of, the diabetes mellitus. S/he may start your dog on insulin treatment before receiving all the laboratory results.
In the diabetic dog without any other illness, the goals of therapy are to achieve near-normal blood glucose levels and minimize the daily variation in those levels. This is important to prevent the complications that develop over time in poorly controlled diabetic patients. Treatment includes insulin administration, diet, and exercise, all of which your veterinarian will discuss with you.
Emergency treatment for dogs with ketoacidois includes intravenous fluids and fast-acting insulin. Once the animal is stable, a regular regime of longer-acting insulin, diet, and exercise can be established.
LABORATORY FINDINGS: fasting hyperglycemia with glucosuria; if the dog has ketoacidosis may see metabolic acidosis, hyponatremia, hyperkalemia, and hypochloremia.
In keeshonds, both parents of affected dogs should be considered carriers and should not be used for further breeding. In other breeds, where less is known about the inheritance of this condition, affected dogs should not be bred, and parents and siblings should be considered potential carriers.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Nelson, R.W. 1995. Diabetes Mellitus. In S.J. Ettinger and E.C. Feldman (eds.). Textbook of Veterinary Internal Medicine, p. 1510-1537. W.B. Saunders Co., Toronto.
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