Diabetes and Your Pet: What You Need to Know

Fluffy, your beloved pet, may have put on a few pounds over the years and gotten a little too … well, fluffy. He’s always had a healthy appetite, but lately you’ve noticed that it seems like he wants breakfast, second breakfast, lunch, tea, dinner, and maybe even a midnight snack.  However, it seems like he’s finally losing some weight even though he’s eating all the time.  Maybe you’ve also noticed that Fluffy is drinking more water, and the kids are complaining about extra “scoops” in the litter box.  On the other hand, Fluffy seems to be a bit less playful and may even be sleeping more than usual (even more than you’d expect a cat to sleep!)  What could be wrong with your kitty?  All of these individual symptoms could be indicators of a variety of feline (and canine) diseases, but taken together, they are classic signs of diabetes.

Diabetes mellitus is estimated to affect one in every 500 dogs and one in every 250 cats.

In the past two months alone, we have diagnosed four of our own patients as diabetic, including two cats and two dogs. All four pets are between the ages of nine and eleven years old. Senior pets are at higher risk for diabetes, as are unspayed female dogs and neutered male cats. Some breeds are also genetically predisposed to the disease, including Miniature Schnauzers, Keeshonds, Miniature and Toy Poodles, and Siamese cats. Feline diabetes is becoming increasingly prevalent among our beloved house pets, and some veterinary experts are even calling it an epidemic. The increase of cats being diagnosed with diabetes is related in large part to our cats’ increase in weight, and almost 60% of pet cats in the USA today are overweight or obese! (Other factors include the fact that cats today are living longer lives; and more cats are being taken by their families to a veterinarian for a diagnosis.) Our dogs have weight problems too, with over 53% of our canine companions being classified as overweight or obese. Dogs and cats carrying extra weight are at greater risk for developing not only diabetes, but also painful arthritis, deadly high blood pressure, kidney disease, and many forms of cancer. As Dr. Ernie Ward, founder of the Association for Pet Obesity Prevention, says, “As a concerned pet owner, you need to understand your pet’s weight is one of the most influential factors of longevity, quality of life, and disease prevention.”

If your cat or dog is diagnosed with diabetes, it’s important to know that the disease is  very manageable; however, it does require a commitment from you and everyone else in the home to keep the pet on a regular schedule for meals, medication, and follow-up visits to your veterinarian. Daily injections of insulin will most likely be required for the rest of your pet’s life, and if the animal’s weight is still a problem you may need to initiate or step-up an exercise or playtime plan. You’ll also need to be prepared for the possibility of low blood sugar episodes or other potential side effects of the disease, and know when and how to take action to help your pet. Your veterinarian will be your guide, but remember that YOU and the other members of your family are an essential part of your pet’s health care team!

What exactly is diabetes? Very simply, diabetes is a malfunction of the body’s ability to convert food into “fuel” for the cells.  Of course, it’s much more complicated than that. Diabetes mellitus is a medical condition that affects the animal’s pancreas, an organ located in the abdomen. The pancreas is essential in the process that converts the food an animal eats into fuel for the body’s cells. The duel-function organ acts as both an exocrine gland, aiding in digestion; and as an endocrine gland, regulating blood sugar.  Insulin is one of several hormones produced by the pancreas.  Diabetes occurs when the pancreas is no longer making sufficient amounts of insulin, or when the body fails to use the insulin correctly.  Without insulin, the sugar (glucose)¹ consumed by your pet cannot be used for energy, so the animal’s digestive system takes protein from the body to convert the protein into energy. When protein is depleted, body fat is converted into energy. This process leads to weight loss, which is usually one of the most obvious symptoms of diabetes. To help maintain your pet’s weight, a diabetic cat must usually be switched to a high protein diet with low carbohydrate content (ideally less than 7% dry matter content); dogs are generally prescribed a low fat/high fiber diet. In addition, in order to address the body’s lack of insulin production, most cats and dogs will require daily injections of the crucial hormone, usually for the rest of their lives.

If the body isn’t able to convert glucose into energy, then where does the sugar go? At first, the excess sugar accumulates in the animal’s blood. Eventually, so much sugar builds up in the bloodstream that the kidneys are overwhelmed and can’t stop the sugar from “spilling over” into the urine. The sugar also draws excess water into the urine. This is why diabetic pets urinate so often and in such large volumes (and why you see those extra big clumps in the cat’s litter box.) In order to replace all that lost fluid and avoid dehydration, a diabetic animal will, of course, drink more water; your pet may seem thirsty all the time, and drink greater amounts every time he goes to the water bowl or pet fountain. It’s not unusual for pets to have “accidents” in the house due to this excessive thirst.

Potential complications of diabetes: As mentioned above, without insulin, glucose begins to spill into the urine.  Excessive urine glucose often leads to bacterial urinary tract infections and increased thirst.  Diabetes also suppresses the animal’s immune system (another factor in the tendency for urinary tract infections, as well as skin infections) and can reduce the body’s ability to heal from any type of wound or recover from surgery.

Another complication of diabetes is cataracts. A cataract is an abnormality of the lens of the eye that causes a cloudy appearance and vision impairment. Diabetic cataracts develop due to excess glucose being transported into the lens. The cells within the lens are unable to process this extra glucose via normal pathways, so the glucose is converted to another type of sugar called sorbitol².  Sorbitol draws in water, causing lens fibers to swell and become disorganized; this leads to cataract formation.  Luckily for our feline friends, diabetic cataracts occur almost exclusively in dogs. Adult cats lack the enzyme that converts glucose to sorbitol in the lens, so even with high blood sugars, cataract formation because of diabetes is rare. Our canine friends are not so lucky. About 80% of all diabetic dogs will develop cataracts within 16 months of being diagnosed with diabetes mellitus³.  Unfortunately, cataracts cannot be dissolved with medications. Surgical removal by a veterinary ophthalmologist is the only effective treatment for this condition, but for most dogs the results of the surgery are good.

The most familiar problems experienced by diabetics are, of course, blood sugar that drops too low (hypoglycemia) and blood sugar that jumps too high (hyperglycemia.) Low blood sugar usually occurs when the pet has received a dose of insulin that is too high, or when someone in the home accidentally gives an extra dose. This is why it is very important to make sure that everyone in the family knows the pet’s feeding and medication schedule, and that each person’s responsibilities for the pet’s care are clearly defined and understood!

If the pet is not eating well or has not eaten at all, it should not be given an insulin injection, because this could cause hypoglycemia; always contact your veterinarian for guidance if your pet is not eating.

Signs of low blood sugar include: weakness, lack of coordination (your pet may stumble or walk in circles,) listlessness, convulsions, and coma. The animal may also be unresponsive to your voice or seem unaware of your presence. If your pet is able to take food, it should immediately be encouraged to eat; if it is unable to eat, you can rub Karo syrup on the animal’s gums.  A low blood sugar event is a medical emergency, and you should contact your pet’s veterinarian or the nearest veterinary emergency hospital without delay.

Sustained high blood sugar can result in a condition called ketoacidosis, which is also a medical emergency. Remember that without insulin, the body cannot convert glucose to energy, so it uses protein next, and then turns to fat for its fuel.  One undesirable byproduct of the body’s conversion of fat to energy is water-soluble molecules called ketones; these are produced by the liver from fatty acids.  Ketoacidosis occurs when those ketones enter the bloodstream and make the blood more acidic. Patients that have developed diabetic ketoacidosis (DKA) are seriously ill and may show the following symptoms: lethargy, lack of appetite, vomiting, unkempt fur, and breath that smells like nail polish remover. An animal with DKA will require hospitalization and intense monitoring in order to recover from the illness.

Common pet owner concerns in caring for diabetics:

  • Giving insulin injections – Many pet owners are understandably apprehensive about giving injections, and worry that they will hurt the animal. With a little instruction from your veterinarian, perhaps a viewing of a helpful video (see below for an example,) and a little practice, it’s really not that difficult!  Insulin needles are usually a fine gauge (so they’re thinner than needles used to give other medications or vaccinations,) and since the insulin injection is given just under the animal’s skin and not into a muscle, most pets barely notice that they’re getting a shot. In addition, if you can learn to give the injection at the same time that your pet is having its breakfast or dinner, the extra distraction of eating may make your pet almost oblivious to the fact that they’re getting the injection.

  • Financial commitment – Diabetic pets require regular visits to their veterinarians. Initially, these visits may be required as often as once a week until the pet’s blood sugar is restored to an acceptable level and the animal’s condition is stabilized. The cost of insulin may be substantial, depending on the type required by the pet (currently there are three different insulins that are commonly used for dogs, and four that are commonly in use for cats.) In addition, while emergency visits and hospitalizations are not inevitable, they should be factored in to the diabetic pet owner’s budgetary considerations. Some expenditures may be reduced by learning to test your pet’s blood sugar at home; in fact, this is often less stressful for the pet and will typically provide a more accurate picture of the animal’s blood sugar levels throughout the day! Ask your veterinarian about home testing devices for cats and dogs, and have the vet instruct you how to use the device and record the results.
  • Additional chronic illnesses – Pet owners who have diabetic friends or family members are probably aware that there can be serious chronic complications that afflict people with diabetes mellitus – such as kidney disease, blood vessel disease, and coronary artery disease. These issues, fortunately, are uncommon in diabetic cats and dogs.

The most important thing to remember if your pet is diagnosed with diabetes is that, with treatment, Fluffy can continue to live a full and happy life! Living with a diabetic will require adjustments to your daily routine, and it can certainly be overwhelming at times … but the increased time spent with your furry friend can also increase the bond between you. If you know what to expect, know what to look for to avoid complications, and know how to help your pet if complications do arise, you and Fluffy can enjoy several more wonderful years together.


¹Glucose is one of the simplest types of sugar and a primary source of energy. Nearly all carbohydrate-containing foods, from fruits to grains, have some amount of glucose, although fruits are usually the highest sources.

²Sorbitol is a sugar alcohol formed by the reduction of glucose.

³Slatter’s Fundamental’s of Veterinary Ophthalmology, Fifth Edition, c. 2013

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