All About Diabetes Mellitus in Dogs and Cats

— By Dr. Ryan Millington — 

Diabetes, or diabetes mellitus, is a common disease found in both dogs and cats. Most pet owners are aware of diabetes, and I would venture to guess that most are at least somewhat familiar with the idea that diabetes is the result of the body not making insulin and, thus, not being able to use glucose.

In its most basic description, that is true; but diabetes is more complicated than that. As a pet owner, it’s most important that you know the signs of diabetes, the risk factors of pets developing diabetes, and how to prevent diabetes in your pet(s).


What are the signs of diabetes?

Although there are some distinct differences in diabetes found in dogs versus cats, the first general signs are similar. The symptoms that are generally the same in both are:

  • Polyuria (urinating very excessively)
  • Polydipsia (drinking very excessively)
  • Lethargy
  • Weight loss

There are many other signs that are often associated with diabetes, especially as a pet becomes more ill, such as nausea/vomiting, poor appetite, and poor hair coat, among other general signs of abnormal behavior.  

Diabetes is not a diagnosis to be made solely on symptoms. Blood tests are necessary to make a diagnosis before any treatment is initiated. These are some common symptoms of diabetes, and if you were to simply do a quick Google search of diabetes, the first three pages of search results will all quote these symptoms. It’s important to note that having a couple of the symptoms does not necessarily mean that your pet has diabetes.

What are the Risk Factors of Pet Diabetes?

There are significant differences in diabetes mellitus (DM) in dogs and cats. Dogs are exclusively afflicted with type I diabetes – they do not get type II DM. Type I diabetes is almost always the result of an immune system disorder, resulting in some specific pancreatitis cells not being able to produce insulin. There are two general underlying causes of type I diabetes: 1. Genetics/hereditary 2. Chronic pancreatitis. There is a strong argument for chronic steroid use causing dogs to be more at risk for diabetes. There aren’t risk factors beyond that for dogs.

Cats, on the other hand, are generally afflicted with type II DM. Although cats can get type I, it is very rare. Obesity is the highest risk factor associated with type II DM. Once again, just because a cat is obese, doesn’t mean they will get diabetes; it just puts them at higher risk of developing it. This should be motivation to keep your cat at a healthy weight.

Is Pet Diabetes Really That Serious?

Diabetes mellitus, regardless of whether it is type I or type II, requires insulin. And once a pet is “regulated,” it is often (but not always) easy. This is particularly true with dogs.

However, finding the correct insulin dose that works for your pet is often difficult. Finding that dose or if there is a delay in starting insulin therapy at all can be quite critical for a pet. If a pet is not receiving enough insulin, they will continue to show symptoms, their body will still be lacking homeostasis, and they will remain at risk for multiple other diseases ranging from simple UTIs, to more severe cases of pancreatitis, kidney disease, and other serious conditions.

If the symptoms of DM are ignored and attributed to a pet just “getting older,” it can lead to a life-threatening situation. DKA, or diabetic ketoacidosis, is a condition in which the body is no longer able to use glucose as an energy source but rather uses fats as its primary energy source. That may sound great for a pet that needs to lose weight; however, if fats are used as the major energy source, there are too many waste products from the breakdown of that fat.

The major waste product is ketones. Ketones are acidic molecules and, in reasonable volumes, are harmless, but when they accumulate in sufficient volume in the body, it creates an acidic state. This wreaks all forms of havoc in the body, requiring rather intensive therapy to treat. And as you can likely deduce, if this is left untreated, it is fatal.

What Kind of Life Can be Expected For My Pet with Diabetes?

The news isn’t all grim here. A pet diagnosed with diabetes mellitus will most often require life-long therapy, but if managed well, pets with diabetes can essentially live a normal life with a life expectancy typical of their species and breed. Managing diabetes well means regular checkups, routine bloodwork checks, and a proper diet. In summary, other than having to get a very small injection once or twice a day, there is nothing different about the lifestyle or quality of life of a pet diagnosed with diabetes.