What Causes High Blood Sugar in Dogs?

what causes high blood sugar in dogs

Blood sugar, or blood glucose, is sugar in the bloodstream delivered to all cells throughout the body for energy. When a dog shows abnormally high levels of glucose, he is said to have hyperglycemia.

This condition is most notably expressed through increased thirst and urination, and will require a visit to the vet for treatment.

So how can you tell if your dog has high blood sugar and what can you do about it? Read on to find out.

High Blood Sugar in Dogs: What Is It?

A simple carbohydrate sugar that circulates in the blood, glucose is essential for supplying energy to a dog’s body. Glucose levels are measured by the amount of sugar transported in the blood at that instant. A healthy dog has a blood glucose level measured between 75 mg to 120 mg.  

What Causes High Blood Sugar In Dogs?

Elevated levels of blood glucose can occur fairly often for various reasons: diet, stress, exertion, and medications. Moderately elevated glucose can indicate infections, inflammatory conditions, and hormonal imbalances.

Persistently high glucose levels, on the other hand, usually points to Diabetes Mellitus.

What Causes High Blood Sugar in Dogs?

From low glucose consumption to high glucose production; physiological causes to infections, there are several possible causes of high blood sugar in dogs.

Causes behind low glucose consumption, which leads to high blood sugar levels

  • Diabetes mellitus: When glucose levels are persistently high, the dog may have diabetes mellitus. This is a disease caused by a loss of pancreatic beta cells, leading to the decreased production of insulin, which is important for processing sugar.
  • Acute pancreatitis: Pancreatitis, the inflammation of the pancreas, can damage cells which produce the sugar-processing hormone, insulin.
  • High progesterone levels
  • Insufficient excretion of waste by the kidneys

Causes of high glucose production:

  • Hyperadrenocorticism: When a tumor enlarges on the pituitary gland, excess levels of cortisol may be released into the bloodstream. This affects the metabolic processes in a dog.
    • Pheochromocytoma: Also known as adrenal gland cancer, a pheochromocytoma is a tumor of the adrenal gland that causes an overproduction of certain hormones.
  • Glucagonoma: Glucagonoma, or pancreatic cancer in dogs, refers to an abnormal growth of cells that secrete glucagon: a hormone which helps metabolize carbohydrates.
  • Pancreatic Neoplasms

Physiological causes

  • Eating food with high levels of sugar, especially human food
  • Exertion
  • Excitement
  • Stress


  • Dental infection
  • Kidney infection
  • Urinary tract infection

Symptoms of High Blood Sugar in Dogs

What Causes High Blood Sugar In Dogs?

Based on the variety of causes of hyperglycemia, symptoms can also vary. Your dog may not even show any serious symptoms, especially in cases of temporary, hormonal, or stress-induced hyperglycemia.

Symptoms of high blood sugar in dogs include:

  • Increased thirst
  • Increased urination
  • Depression, expressed in loss of appetite, changes in sleeping habits, loss of interest in activity, and/or seclusion
  • Severe depression, as seen in dogs with very high blood sugar levels
  • Weight loss
  • Obesity
  • Excessive hunger
  • Dehydration
  • Wounds that won’t heal. Excess sugar feeds fungus and bacteria, increasing the infection.
  • Tissue damage from the burning effect of excess sugar in the tissue
  • Cataracts, seen as a cloudiness in the lens of the dog’s eye
  • Bloodshot eyes from inflamed blood vessels
  • Liver enlargement
  • Nerve damage in the legs

Diagnosing High Blood Sugar in Dogs

If you suspect your dog is hyperglycemic, take your dog to the veterinarian. He will conduct a complete blood profile including a chemical blood profile, complete blood count, and urinalysis.

More specific tests may be required to diagnose the underlying cause. Be sure to give a thorough history of your dog’s health, the onset of symptoms, and any situations which might have led to this. Giving your veterinarian this history may help uncover which organs are involved, such as an undiagnosed disease of the pancreas.

Similarly, be sure to let your veterinarian know if your dog has had any previous infections in the body. These infections may still be present, leading to a spike in glucose levels.

Treating High Blood Sugar in Dogs

Once your veterinarian properly determines the underlying cause of hyperglycemia, he or she will prescribe the proper treatment. Treatment can involve a variety of plans: minimizing stress for physiological cases; insulin and diet modification for diabetic dogs; medication for issues such as hyperadrenocorticism, and more.

Working with your vet to find the underlying cause and proper treatment, you can be sure to help your dog maintain stable levels of blood sugar to continue his proper, healthy lifestyle.

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