Diabetes Mellitus in Dogs

Sad looking dog lying on carpet
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Diabetes mellitus is an endocrine disease that commonly occurs in dogs, as well as cats and humans. The normal pancreas has two essential functions. 1) It secretes enzymes that assist with digestion in the small intestine. 2) It produces a hormone called insulin that enables the body to absorb glucose from the bloodstream. Diabetes mellitus occurs when the pancreas is unable to produce sufficient amounts of insulin.

Without insulin, the body's cells cannot absorb the glucose, its major fuel source, and the body goes into a type of starvation mode. Meanwhile, excessive amounts of glucose remain in the bloodstream.

Types of Diabetes Mellitus

In humans, diabetes is divided into two categories. Type I is characterized by an inability of the pancreas to produce any insulin. This is also called juvenile onset or insulin-dependent diabetes. Type II, also called adult-onset diabetes, occurs when the pancreas does not produce enough insulin. This type is considered non-insulin dependent.

In animals, diabetes is not typically broken down into these types. While cats can develop insulin dependent or non-insulin dependent forms, non-insulin dependent diabetes in dogs is extremely rare. Canine diabetes is nearly always insulin-dependent.

Risk Factors for Diabetes Mellitus in Dogs

There are a number of reasons dogs develop diabetes mellitus, and the exact cause is often not determined.

Some dogs are genetically predisposed to the disease, so this is something you can investigate if you know your dog's parents or littermates. Another potential cause of diabetes is obesity, which is preventable with proper diet and exercise. Pancreatitis, insulitis or a concurrent hormonal disease can also lead to the development of diabetes.

This is all the more reason to be an advocate for your dog's health by visiting your veterinarian often and taking steps to keep your dog healthy.

Canine Diabetes Mellitus Symptoms

Dogs can show a variety of signs that indicate diabetes mellitus. Unfortunately, these symptoms can also indicate the presence of another disorder, so be sure to consult your vet if you notice any signs of illness. The most common symptoms of diabetes include the following:

  • Increased thirst
  • Increased urination
  • Increased appetite
  • Weight loss
  • Vision loss (due to formation of cataracts)
  • Poor hair coat

One or more of the above symptoms may occur in diabetic dogs, but even dogs with no symptoms can still have a health problem. For this reason, your dog should visit the vet for a wellness exam at least once or twice a year.

Secondary Effects of Diabetes Mellitus

Dogs with diabetes mellitus have an excess amount of glucose in the blood. The excess sugar can make its way to the lens of the eye, causing cataract formation. Additionally, high blood sugar levels may become too much for the kidneys to filter, and glucose may "spill" into the urine and enter the bladder. Because sugar promotes bacterial growth, urinary tract infections (UTIs) often occur.

The overabundance of sugar can also lead to bacterial infections elsewhere in the diabetic dog.

The most serious complications of diabetes mellitus are ketoacidosis and hypoglycemia/insulin shock.

Diabetic Ketoacidosis

Diabetes mellitus causes an inability to metabolize glucose, making the body think it is starving. In search of energy sources, the body breaks down fatty acids and causes the liver to produce organic acids called ketones. Excessive amounts of ketones can cause a life-threatening condition called diabetic ketoacidosis (DKA). Signs include vomiting, loss of appetite, depression, weakness, and breath that smells of acetone. DKA is a serious complication of diabetes mellitus that can lead to anemia, acute renal failure, electrolyte imbalance and neurological disorders. DKA occurs in undiagnosed or unregulated diabetics.


Hypoglycemia, or very low blood glucose, is an emergency situation. Also called insulin shock, diabetic hypoglycemia occurs when the body receives too much insulin. Because glucose is constantly required by the brain to utilize oxygen, hypoglycemia can lead to seizures, coma, brain damage or even death. Early signs of low blood sugar include drunkenness, dizziness, and disorientation. To raise the blood sugar, give a tablespoon of corn syrup or honey by mouth, rubbing it on the gums if possible. If no improvement occurs, immediately see your veterinarian for emergency treatment.

Diagnosing Diabetes Mellitus in Dogs

Providing an accurate, thorough history to your veterinarian can be the key to discovering diabetes in your dog. The first step in the official diagnosis of diabetes is measurement of the blood glucose for consistently high levels. Urinalysis is also performed to check for glucose, as non-diabetics rarely have any glucose in the urine. As part of the diagnostic process, blood serum chemistry will be and a complete blood count will be run. These test look at your dog's overall health and organ function. In some cases, more specific blood tests and/or abdominal ultrasound will be recommended.

Once your veterinarian has confirmed a diagnosis, a treatment plan will be developed for your dog. While there is no cure for diabetes mellitus, it can usually be managed. Most diabetic dogs can go on to live a normal life with proper ongoing treatment and monitoring.

NEXT: Diabetes Treatment for Dogs