Diabetes Mellitus in Dogs
Diabetes mellitus is a disease state by which the body suffers from either an absolute shortage of insulin (Type I or insulin dependent), or from an incorrect response from the cells to the insulin that is being produced, a condition termed insulin resistance (Type II or insulin resistant). Both of these conditions will prevent the muscles and organs from converting glucose to energy and will result in excessive amounts of glucose in the blood, which is also referred to as hyperglycemia.
Diabetes is a disorder of carbohydrate, protein, and fat metabolism caused by an absolute or relative insulin deficiency. Metabolism refers to how the body digests and uses food for growth and energy; this process is largely dependent on a sufficient amount of insulin in the body.
Insulin is a hormone that is produced in the pancreas and released into the cells in response to the digestive conversion of carbohydrates and protein into glucose in the bloodstream. Much of the food that is ingested is broken down into glucose, a type of sugar in the blood and one of the body's main sources of energy. Appropriate insulin function will trigger the liver and muscles to take up glucose from the blood cells, converting it to energy.
Diabetes, a common condition for humans, is also relatively common in domestic animals like dogs. In Type I diabetes, the pancreas has stopped producing insulin entirely. Affected dogs are dependent on daily insulin injections for maintaining blood sugar balance (insulin dependent diabetes mellitus – IDDM). This is the most commonly diagnosed type of diabetes in dogs.
In Type 2 diabetes, the pancreas can still produce insulin, but the body cannot adequately respond to it. While the disease process is not exactly the same in dogs as it is in people, dogs can develop insulin resistant diabetes (IRD.)
An affected dog will be hungry a lot of the time. Since glucose is not making it to the brain, glucose levels in the brain are too low for the brain to register that it is receiving food. Because insulin is not giving the muscles and organs the signal to convert glucose to energy, the excess glucose in the blood will be carried out of the body in urine instead of being used for energy and there will be a concurrent lack of energy. The glucose ends up in the urine, where it interferes with normal urine concentration and leads to an increase in urination. The pet becomes dehydrated as a result of the abnormal water loss, so there is also increased thirst. The liver is adversely affected by this condition, as are the eyes and kidneys. Affected pets are also at increased risk for systemic infections, dental disease, and cataracts.
IDDM diabetes can occur at any age. IRD diabetes is seen more frequently in older, obese, and desexed dogs, though it can also occur at any age.
Symptoms and Types
- Excessive urination
- Excessive thirst
- Weight loss even with normal appetite
- Elevated blood glucose
- Glucose in the urine
- Anorexia – complete loss of appetite
- Lethargy and depression
- Worsening weight loss
- Recurrent infections
Development of Ketoacidosis – A life threatening complication of unregulated diabetes, diabetic ketoacidosis (DKA) is a metabolic acidosis caused by the breakdown in the liver of fat to ketones in response to starvation.