Signs of Diabetes in Dogs

Signs of Diabetes in Dogs

Written by: Alexa Waltz

Diabetes is a hot topic in human and animal health! Most people have some understanding of this serious condition because a family member, friend, acquaintance, or maybe even a family pet is living with diabetes. Are you suspecting that your pup may have diabetes, or just want to learn more about your dog’s recent diagnosis? Keep reading for a discussion of what diabetes in dogs is all about.

What Is Diabetes?

Diabetes is an endocrine disease that can affect dogs and involves a peculiar little organ called the pancreas. The pancreas lives in the abdomen and is tucked up near the stomach and intestines. A healthy pancreas is essential to digestion and glucose metabolism in the body! You may recall that glucose is what the body uses for energy in all of its organs. Problems start to occur if the amount of glucose in the bloodstream is too high or too low.  The pancreas plays an essential role in making sure glucose levels in the body are optimal and safe to keep everything working in tip-top shape. 

Glucose is present in foods that we eat and is the predominant energy source for the brain, muscles, nerves, and all organs. Think of glucose as the best fuel that our cells use to perform ALL their functions! The process of how glucose is digested, stored, released, and absorbed is complicated, but here are some basics. 

During digestion, foods are broken down by the stomach and intestines into tiny molecules of glucose, fat, water, vitamins, minerals, and proteins. These molecules are tiny enough to be absorbed across the intestinal wall and into the bloodstream where they circulate around the body waiting to be used by cells or stored for later within the organs. The body needs and uses all types of different molecules to carry out the functions of our vital organs in order to sustain life. For today’s discussion, we will specifically focus on glucose molecules as they are the main concern in diabetes. 

After digesting a meal, you can imagine that the glucose level circulating around in the blood increases, looking to either be used by the body or stored away for later. The pancreas has specialized “beta cells” that detect glucose levels in the bloodstream. When the glucose level in the bloodstream is too high, the beta cells secrete a hormone called insulin. Insulin is released into the bloodstream and attaches to the surface of cells, allowing glucose to enter into the cell and be used as energy. Once inside, glucose powers all of the cellular processes. Brain cells have the highest energy demand in the body and NEED glucose to function, same with kidney cells, skin cells, and muscle cells … ALL CELLS need glucose inside of them to function! 

In short, insulin can be thought of as the key that opens a cell’s door to the essential energy source called glucose. Without insulin, glucose flows through the bloodstream, unused. Meanwhile, the cells are deprived of fuel and have to find alternative and less effective energy sources to keep carrying on with life itself. 

In patients with diabetes, this is exactly what happens. Damage to the beta cells of the pancreas means that the ability to detect glucose levels and secrete insulin is impaired. Without enough insulin, glucose builds up in the bloodstream but all of the cells and organs in the body begin to starve. There may be plenty of glucose available in the bloodstream, but it is not accessible to the cells because it can’t get inside of them. In this state of glucose starvation, the body desperately looks for another energy source, which is fat. Fat is much less efficient as a fuel for the body and, unfortunately, byproducts of fat breakdown called “ketones” build up in the bloodstream. Ketones are very harmful in that they lower the blood pH, becoming more acidic. When insulin is absent for an extended period of time, a dangerously high level of glucose and ketones can cause a health crisis called diabetic ketoacidosis (more on this later!). 

The above process is referred to as “Insulin dependent diabetes mellitus” (aka “Type 1” or “juvenile diabetes” in humans) and is the most common type of diabetes in dogs. We are not sure what destroys the insulin-producing beta cells in the pancreas but immune mediated causes, recurrent pancreatitis, Cushing’s disease, and genetics are the likely culprits. Diabetes most often affects middle aged to older dogs and some breeds have a higher incidence of occurrence. The commonly affected breeds are Cocker Spaniels, Golden Retrievers, Dachshunds, Dobermans, German Shepherds, Pomeranians, Terriers, Keeshonds, Miniature Schnauzers, Samoyeds, Poodles, and Labrador Retrievers.

Signs of Diabetes in Dogs

What are the symptoms of diabetes in dogs?

Increased Thirst and Urination

Increased thirst and urination are by far the most common symptoms noticed by pet parents preceding their dog’s diagnosis of canine diabetes. Thirst can become so extreme that dogs not only drain their water bowl daily in record time, but they go looking for extra water sources around the house, like the toilet or puddles outside. Urine accidents in the house may be noticed too, simply due to the increased volume of urine present and the urgency to potty. Pet parents also may note an increased appetite, weight loss, and decreased muscle mass alongside the thirst and urination. This loss in muscle mass, or a more “bony” appearance, is because of the body breaking down fat stores in order to maintain energy delivery to the cells in the absence of glucose.

Why do dogs drink and pee so much with diabetes? In a healthy dog, the kidneys ensure that there is no glucose present in the urine. With diabetes, there is such a high level of glucose in the blood (4-5 times normal!) that it overwhelms normal kidney functions and some of that extra glucose ends up in the urine. That glucose will also drag with it quite a bit of fluid due to the osmotic gradient (fluid will naturally follow that dissolved glucose into the urine). This great fluid loss is what creates that huge volume of urine, and at the same time makes your dog so dehydrated that their brain is begging them to drink more and more and more to compensate!

Diabetic Ketoacidosis

Some dogs that experience extremely high blood glucose levels and an absence of insulin for an extended period may have a dangerous complication called Diabetic Ketoacidosis. This most commonly happens with patients who are pre-diagnosis, meaning they are not known to be diabetic yet. It can also happen in diabetic dogs that are not well-regulated with external insulin sources. As mentioned earlier, that lack of insulin and the starvation of cells for energy will cause fat burning and the production of ketone bodies as a metabolic byproduct. Ketones are acidic, lower the pH of the blood, cause electrolyte imbalances, and disrupt cell functions — all very, very dangerous for overall body health. These dogs will get very sick, stop eating and drinking, may vomit, may be panting or breathing abnormally deep, have low energy, and may have trouble walking and responding. It is extremely important that these dogs receive emergency care immediately, as this condition is life threatening.

How Is Diabetes Diagnosed in Dogs?

Diabetes is usually a pretty straightforward diagnosis in dogs. A quick blood and urine test at your veterinary clinic should be able to indicate the presence of diabetes. The blood test will show hyperglycemia, aka increased blood glucose. Normal blood glucose levels for dogs are about 80-120 mg/dL, but diabetic dogs can be in the 500-600+ mg/dL range! The urine test also will show glucosuria, aka glucose present in the urine. Normally, the kidney ensures there is no glucose in the urine, but when the circulating blood levels are above approximately 200 mg/dL the kidneys will be overwhelmed and glucose will spill into the urine as described above.

Some other important changes seen on lab work indicating diabetes, and the emergency condition of diabetic ketoacidosis, are ketonuria (ketones present in the urine indicating excessive fat breakdown), low blood pH, abnormal electrolyte levels, and increased markers for dehydration. It is also very important to perform a urine culture looking for bacterial growth from a urine sample. Bladder infections are very common in diabetic dogs since glucose is present in their urine (and bacteria use glucose for energy, too!). Sometimes it is easy to miss a bladder infection on the urinalysis test alone since the urine is so dilute and the bacteria are spread so far apart, but the urine culture is a more sensitive test to check for the presence of bacteria.

Occasionally, the results of blood and urine testing are not convincing enough, and the numbers appear “borderline”. A special blood test called fructosamine can be sent to a lab to gather more info. This test is similar to the human “A1C” test and will indicate the average glucose levels present in the bloodstream over the previous few weeks. An elevated fructosamine can indicate the glucose has been elevated over a longer period of time.

One peculiar side effect of hyperglycemia in dogs occurs within the lens of the eyeball resulting in the formation of diabetic cataracts. Glucose is converted to sorbitol to nourish the lens, and prolonged hyperglycemia will increase the fluid present, disrupt those delicate lens fibers, and create a cataract. Diabetic cataracts will cause complications within the eye and blindness within a few months. Diabetic cataracts require immediate attention, so if you see some cloudiness in your pup’s eyes, or they seem to have eye pain or vision issues, please consult your vet right away!  

Beyond The Diagnosis

Once diabetes has been confirmed in your pup, the adventure begins. Luckily, diabetes is very manageable in dogs, but it does take a devoted pet parent and close adherence to the plan you create with your vet. Luckily, we have many effective ways to manage and  treat diabetes in dogs that result in your pup living their best life despite their diagnosis! 

For questions and further discussion on diabetes in dogs, your AskVet veterinarians are here to help! If you have any questions about your dog’s medical condition or are wondering whether your dog’s symptoms are an urgent issue, then all you have to do is AskVet. We are here 24/7 to help you and your dog!


Written by:

Alexa Waltz, DVM

Dr. Waltz was raised near the beaches of Southern California but has spent her adult life living all over the beautiful United States while serving in the military and as a military spouse. She left California for the first time to pursue a career as a veterinarian at Louisiana State University School of Veterinary Medicine and graduated as a Doctor of Veterinary Medicine in 2006. She was accepted into the US Army Health Professionals Scholarship Program during vet school and upon graduation spent her military years as a veterinarian in San Diego working for the US Marine Corps and US Navy Military Working Dog programs as well as caring for pets of service members. After her military service, she became a civilian veterinarian and continued as a small animal general practitioner at clinics in California, Rhode Island, Colorado, and Maryland. Dr Waltz loves to see her “in person” patients just as much as communicating with and assisting pet parents virtually on AskVet. Dr Waltz is also a Mom to 3 humans, 2 guinea pigs, and 1 Australian Shepherd and in her spare time she loves traveling, adventures, exercising, and doing just about anything out in nature!

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