Diabetes in Dogs and Cats: Everything You Need to Know

Jessica Vogelsang, DVM
By Jessica Vogelsang, DVM on Sep. 2, 2016

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?


How is Diabetes Diagnosed in Dogs and Cats?

An initial diagnosis of diabetes does not require special testing outside of standard bloodwork and urinalysis. The main criterion in blood testing is an elevated blood glucose, though other abnormalities are also common. A urinalysis is also highly recommended as the presence of glucose in the urine is one of the hallmarks of diabetes.

Additional tests, such as urine culture to check for urinary tract infections, thyroid testing, and/or x-rays, are also commonly ordered to help gain a thorough picture of the pet’s current state of health.

Because diabetes affects every pet differently, and because some pets are more severely ill at the time of diagnosis than others, an accurate assessment is necessary so that your veterinarian can provide the most effective and timely treatment.

How is Diabetes Treated in Dogs and Cats?

In pets with clinical signs of disease, insulin injections are the mainstay of treatment for both dogs and cats. In cats, glargine and PZI are the insulins most commonly used. In dogs, Lente, NPH, and Vetsulin insulins are the first line insulins used in treatment. Each has its pros and cons in terms of how long it lasts in the bloodstream, how easy it is for owners to obtain, and reasonable cost. For those reasons, the most current American Animal Hospital Association Diabetes Management Guidelines suggest multiple options so that veterinarians and owners can select the best insulin for the pet as a team.

While many owners of a newly diagnosed diabetic worry about administering the injections, most adjust quickly. Insulin injections are given twice a day, timed with a meal, and because of the tiny needle size and volume administered, even the most reticent owners learn quickly that pets don’t seem to mind the shots.

How Quickly Do Pets with Diabetes Improve?

Managing a pet’s blood sugar is both an art and a science. Determining the proper insulin dose does not often happen right away; it can take some time before you and your vet arrive at the right amount of insulin. Many factors, such as stress and illness, can cause variances in blood sugar from day to day, so owners who are attempting to monitor their pets’ blood glucose may find it very confusing, especially in the beginning.

Your veterinarian may suggest a glucose curve—that is, testing blood glucose over the course of a day to make sure the prescribed insulin is properly managing the body’s blood sugar. Some veterinarians also monitor fructosamine, a value obtained from a single blood test that gives a “big picture” look at how the blood glucose has been doing over a several week period.

Next: What Role Does Diet Play in Diabetes Management for Pets?


What Role Does Diet Play in Diabetes Management for Pets?

Everyone has a story about a friend who changed their cat’s diet and no longer needed insulin. While that isn’t the most common outcome, remission is possible in certain cases. And in any case, nutrition is a key component for managing the symptoms for all diabetics.

Dr. Jennifer Larsen, a diplomate of the American College of Veterinary Nutrition and Associate Professor of clinical nutrition at the University of California Davis, stresses the importance of an individualized approach. While obesity is a critical risk factor in diabetes, pets of any weight can suffer from diabetes.

“In cats, the loss of body fat can result in remission, while for dogs, improved control (of symptoms) is an important goal,” said Larsen. “Likewise, reversing inappropriate or unwanted weight loss in a thin dog or cat is also important.”

Veterinarians look at two main factors in diabetic diets: the makeup of the diet, and the timing of the feedings.

Dr. Larsen stressed the importance of the timing of meals as much as the amount of the meal itself. “For dogs, feeding management in terms of consistency is important,” says Larsen.

“Since the insulin dose is titrated to the diet, the same amount of the same [food] should be fed at the same times every day.” However, she added that “this appears to be much less important for cats.”

Contrary to common perception, veterinarians do not immediately jump to a new diet in newly diagnosed diabetic pets. Dr. Larson explains that “unless there is a concurrent disease that should be addressed, such as obesity or pancreatitis, and assuming the diet is otherwise appropriate, I usually do not change the diet initially.”

“Ensuring that all of the other aspects of managing a diabetic pet are well controlled is a priority,” says Larsen. For many families, the stress of managing injections and monitoring a pet’s health is challenge enough, and Larsen likes to take a big-picture approach.

Dr. Lisa Weeth, also a board certified veterinary nutritionist, agrees. “While I don’t change the diet initially for canine diabetics, I have found that increasing total dietary fiber does help with managing most cases. It won’t eliminate the need for insulin, but it does help even out the clinical signs throughout the day”

“Avoiding snacks in between meals is important for dogs,” says Weeth. “I have owners either stop treats or confine them to a two hour window after the main meals and account for that in my diet plan.”

High fiber diets are still the mainstay for both dogs and cats. While many people are now advocating a low carbohydrate, high fat and protein diet for diabetics, Larsen urges caution. “These diets are often higher in energy density and not ideal if weight loss is needed, since the volume fed may be too low to satisfy the cat and the owner. Again, an individualized approach is best.”

Weeth also emphasizes the fact that diabetes requirements vary widely depending on the pet and that there is no “one size fits all” approach. Some cats who begin as insulin resistant Type 2 diabetics can progress to insulin deficient Type 1 diabetes over time.

“In Type 1 diabetics, reducing total carb intake or adding fiber may help reduce the insulin dosage, but it doesn’t eliminate the need. For Type 2 diabetics, insulin may be necessary to control the hyperglycemia initially, but if you are able to address the confounding factors (secondary influences), the cat may revert to a non-insulin dependent state for a period of time.”

Diabetes doesn’t have to be an insurmountable problem. Successful management is a team approach with an involved veterinarian and a dedicated and patient owner. If your pet has been recently diagnosed with diabetes, take a deep breath and then get ready to learn some new skills. It’s all worth it.

Jessica Vogelsang, DVM


Jessica Vogelsang, DVM


Jessica Vogelsang, DVM, is a person who loves too many topics to be able to stick to one descriptor: writing, dogs, communication, cats,...

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