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Diabetes in Dogs and Cats: Everything You Need to Know

by Jessica Vogelsang, DVM


Certain triggers cause us vet types to start thinking in overdrive during our examinations of pets. A seemingly innocent question, like “How’s his appetite? Has he been drinking more or less than usual?” can actually represent a significant clue in our hunt for answers. A dog or cat, for example, who suddenly starts drinking and urinating a ton more than usual is giving us a big hint that something is wrong with its body—and of the several possible causes, diabetes is one that owners seem to dread hearing the most.


As one of the most common health conditions in middle-aged cats and dogs, a diagnosis of diabetes mellitus is frightening for owners. And it’s true, diabetes is usually a lifelong condition that requires vigilance on the part of owners in order to control. But that also leads to the good news: in many cases it can be managed, and often pets with diabetes continue on to lead long and happy lives.


What is Diabetes in Dogs and Cats?


Diabetes can refer to two unrelated conditions in veterinary medicine: diabetes mellitus (sugar diabetes), and less common diabetes insipidus (water diabetes). As diabetes insipidus is a much rarer condition with a completely different cause and treatment, this article focuses on the prevalent type of diabetes: diabetes mellitus.


The pancreas is an essential organ; it is here that the beta cells that produce insulin reside. Insulin is a hormone that helps the glucose (sugar) in the bloodstream to enter the body’s cells to be used as an energy source. Diabetes is a condition caused by a loss or dysfunction of the beta cells of the pancreas. In some cases, the pancreas completely loses the ability to manufacture insulin—insulin deficient diabetes, also described as Type 1 diabetes—and the pet is dependent on external administration of the hormone. In other instances, the pet can manufacture insulin, but the body doesn’t respond to it (insulin resistant diabetes, or Type 2 diabetes.)


While it is assumed that pets are either Type 1 or Type 2 diabetics, that isn’t always the case. Rather than being one or the other, diabetes severity can exist on a spectrum. A recent study published in the Journal of Veterinary Internal Medicine shows that an individual pet’s condition may be more fluid than initially thought. For example, I had learned in school that dogs were almost exclusively Type 1 diabetics, and cats were almost always Type 2. Now we know that isn’t necessarily always the case.


What Causes Diabetes in Dogs and Cats?


There is no one single cause of diabetes in dogs and cats. In some pets, it is a genetic condition; certain breeds such as Australian terriers, Beagles, Samoyeds, and Burmese are at higher risk. Underlying medical conditions such as obesity, pituitary disease, and adrenal disease can predispose a pet to developing diabetes. Medications such as steroids can also induce diabetes in dogs and cats.


What Are the Signs of Diabetes in Dogs and Cats?


No matter the cause, all diabetics have elevated blood sugar that spills over into the urine, causing a predictable array of clinical signs:

  • Drinking and urinating much more frequently. The presence of glucose in the urine prevents the kidneys from effectively doing their job re-absorbing water into the bloodstream.
  • Increased hunger. Despite the high levels of glucose in the blood, the body can’t utilize it for energy. It’s kind of like sitting at a buffet with your mouth taped shut; there’s food everywhere, but it’s not doing you any good. So the body continues to signal pets to eat more and more to raise blood glucose levels.
  • Weight loss. Again, despite the increased appetite, the body can’t do anything with the calories being swallowed, so patients lose weight.
  • Additional signs may include vomiting, poor coat condition, cataracts in dogs, and abnormal gait in cats.


Left untreated, diabetes can lead to liver dysfunction and a life-threatening condition called ketoacidosis. A diabetic pet that is vomiting or disoriented should be evaluated immediately. Without aggressive treatment, diabetic ketoacidosis can lead to brain swelling, kidney failure, pancreatitis, and rapid death.


Next: How is Diabetes Diagnosed in Dogs and Cats?