Reviewed for accuracy on August 26, 2019, by Dr. Katie Grzyb, DVM
Diabetes mellitus can affect dogs of any age, but early detection is the most important step in ensuring that your dog continues living a happy, healthy life.
Annual wellness visits are essential for early disease detection, but if you know the signs and symptoms of diabetes in dogs, you can recognize the problem between checkups and bring it to your veterinarian’s attention.
Keep in mind that the symptoms of diabetes in dogs can overlap with other diseases. For example, kidney and liver disease are linked to increased urination and thirst, while hyperthyroidism and some cancers can cause increased hunger.
When in doubt, take your dog to her veterinarian for a full evaluation to rule out diabetes or other conditions.
Here are the most common symptoms of diabetes in dogs.
You might start to see puddles on the floor or notice that your dog is nudging you to get out of the house more to pee.
Increased urination, which veterinarians refer to as polyuria, is one of the most common reasons that pet parents bring their dogs in for evaluation, says Dr. Jessica Romine, DVM, DACVIM, from BluePearl Pet Hospital in Southfield, Michigan.
Polyuria is caused by blood sugar spilling from the bloodstream into the urine, Dr. Romine explains. “There is a renal threshold where the kidney can no longer filter glucose fast enough to keep it in the blood, and it leaks into the urine. When this occurs, it pulls water with it, and the dog will begin to urinate more and more.”
Excessive thirst (polydipsia), is linked to increased urination, but not in the way that you might think.
“Oftentimes owners will think they are urinating more because they’re drinking more, but it’s actually the other way around,” says Dr. Romine.
“As the dog urinates more and more, they will start to become dehydrated, so they drink larger and larger amounts to keep up.”
A diabetic dog may develop an insatiable appetite (polyphagia), a symptom that veterinarians attribute to an imbalance of insulin, a hormone created by the pancreas to help control blood sugar.
“Because of the lack of insulin, they’re hungry all the time. The body can’t perceive that it has glucose, so it thinks that it’s starving, and is always trying to eat,” says Dr. Ellen Behrend, VMD, PhD, DACVIM, the Joezy Griffin Professor in the Department of Clinical Sciences at the College of Veterinary Medicine of Auburn University in Alabama.
Many conditions can cause weight loss in dogs, including cancer, gastrointestinal disease, liver disease and kidney disease, says Dr. Romine.
When that weight loss—which can start gradually or suddenly—is coupled with a normal appetite, it can be a sign of diabetes.
“With insulin not working to get glucose into the brain, heart and other essential organs for energy, the body will start to break down muscle and fat to use those proteins and fat instead, leading to weight loss,” explains Dr. Romine.
Up to 80% of dogs with diabetes mellitus will eventually develop some degree of cataracts, says Dr. Romine. Cataracts are one of the most common long-term complications seen in dogs with diabetes.
In a healthy dog, the lens absorbs glucose from the eye fluid and converts the excess into sorbitol, she says. “When there is a large amount of glucose, a large amount of sorbitol is produced. Sorbitol has a strong pull on water, so water enters the lens and causes distortion of the fibers, blocking light from passing through.”
This can cause your dog’s eyes to appear to be cloudy.
As a result of cataract formation, diabetic dogs are at an increased risk for blindness.
A cataract that completely prevents light from reaching the retina on the back of the eye causes vision loss, says Dr. Romine. “The good news is that as long as any secondary inflammation from the cataracts is controlled, most blind dogs do very well because they have excellent senses of smell and hearing and adapt to their environments.”
In some cases, blindness can be reversed by surgically removing the abnormal lens.
Blindness (and cataract formation) can occur over a period of weeks to months, or in as little as 24 hours, she says. “It can also happen early or late in the course of diabetes.”
Untreated diabetic dogs will tend to have poor coat and skin quality.
“When the body is not getting the nutrition it needs because insulin isn’t working, and a dog is becoming chronically dehydrated from the increased water loss in the urine, their haircoat will often start to lose its luster and thin out, and dogs will start to have dandruff and dry, scaly skin,” says Dr. Romine.
These conditions improve with insulin therapy, says Dr. Romine, because “there is now enough energy and nutrition to put towards healthy fur, and not just maintaining critical organ function.”
Vomiting is typically not something that occurs in uncomplicated diabetes cases, says Dr. Behrend. “If diabetes goes untreated, the dog can go into diabetic ketoacidosis (DKA), where you see vomiting, lethargy and a poor appetite. At this point, it’s an emergency situation that requires hospitalization.” (Other DKA dog diabetes symptoms include panting and weakness.)
DKA can occur when the blood sugar is very high and little-to-no insulin is pulling the glucose into the tissues, says Dr. Romine. “The body will start to produce ketones for energy, but this is not a sustainable pattern; the blood becomes acidic, and the body’s enzymes start to malfunction.”
In some cases of DKA, you may notice a distinctive odor to your dog’s breath, similar to the smell of nail polish remover, says Dr. Behrend. However, the odor is relatively uncommon and not everyone will notice it.
“Some dogs will be less interactive with their families because they do not have the energy, and will tire faster after playing or going on walks,” says Dr. Romine.
When sugar is trapped in the bloodstream and can’t enter the tissue, the body is deprived of the glucose required for energy, says Dr. Romine. “In addition, the high blood sugar can cause electrolyte imbalances, including low sodium, low potassium and low phosphorous, making the nerves not fire normally.”
Your dog may stumble, appear to be stiff or have difficulty lying down.
“Dogs with diabetes can develop muscle weakness as a result of the lack of glucose going to their muscles,” says Dr. Romine.
Another less common cause is diabetic neuropathy, which can lead to chronic or progressive hindlimb weakness, knuckling, muscle atrophy, and general weakness.
Although not as common, a diabetic dog can develop dropped hocks, a condition in which the rear legs are closer to the ground than where they should be, says Dr. Behrend. “Owners can notice that the dog is standing weirdly or walking weirdly. It’s kind of subtle.”
Learning to spot the signs of dog diabetes and communicating with your veterinarian can help you intervene early on.
Diabetes in dogs is usually a manageable disease, says Dr. Romine, “and most diabetic dogs can do very well once an insulin routine is developed.”
It’s important to note that although diabetes in puppies is not as common as it is in older dogs, it can still occur. Always check with your veterinarian if you notice anything unusual, whether your furred family member is an older dog or a puppy.
By: Paula Fitzsimmons