Related: Diabetes Mellitus in Cats
Diabetes in dogs is a commonly diagnosed disease. When the pancreas is affected and the blood glucose (blood sugar) becomes elevated as a result, the disease is termed canine diabetes mellitus. This differentiates the disease from the other form of diabetes, diabetes insipidus.
Causes of Diabetes Mellitus in Dogs
Diabetes mellitus occurs when specific cells within the pancreas, known as beta cells, are destroyed. Beta cells are responsible for secreting insulin, the hormone that is necessary to help regulate the blood glucose level. When the insulin level becomes decreased, the blood glucose level will increase. In diabetes mellitus, insulin levels are abnormally low because of the pancreatic destruction and, as a result, the blood glucose level will be excessively high.
Canine diabetes mellitus can be caused by several different things.
- Most cases of diabetes mellitus are believed to be related to immune-mediated disease in which the dog's immune system systematically destroys the pancreatic beta cells.
- Canine diabetes mellitus can also be caused by chronic pancreatitis. In this case, the constant inflammation within the pancreas leads to the destruction of beta cells.
- Certain drugs may also be responsible for causing diabetes mellitus. These include corticosteroids and megestrol acetate.
- Because some breeds have a higher incidence of diabetes mellitus, it is also believed that there may a genetic predisposition to the disease.
Classification of Diabetes Mellitus
Diabetes mellitus in people can be classified as being insulin-dependent (Type I) or non-insulin-dependent (Type II). In dogs, almost all cases of diabetes mellitus seen are Type I because the beta cells within the pancreas are destroyed and are therefore non-functional. When the beta cells cannot function to produce insulin, supplemental insulin (usually in the form of insulin injections) will be necessary to treat the condition.
There is also a Type III diabetes classification that involves insulin interference by certain diseases, conditions and/or drugs. Examples include hyperadrenocorticism (Cushing's disease), acromegaly and diestrus (part of the reproductive or heat cycle.)
Symptoms of Canine Diabetes Mellitus
The most common symptoms seen in dogs with diabetes mellitus are:
- increased thirst (sometimes called polydipsia)
- increased urination (sometimes called polyuria)
- increased appetite (sometimes called polydipsia)
- weight loss, which may occur despite an increased appetite
Cataracts can also occur in diabetic dogs because of the effects of increased glucose levels on the lens of the eyes.
As the disease progresses, symptoms may become more serious and may eventually become life-threatening if treatment is not instituted.
Diabetes tends to be seen most commonly in middle-aged dogs but it can occur younger in some breeds, such as the Golden Retriever and the Keeshond.
Some breeds appear to be more more likely to develop diabetes mellitus. These breeds include:
- German Shepherd dogs
Diabetes mellitus is a common condition in dogs. Canine diabetes mellitus is usually insulin-dependent and treatment requires insulin injections, often given twice daily.