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Blood glucose levels are an important indicator of health in our companion animals. When you take your pet to the veterinarian, blood glucose measurement often is a part of your pet’s basic bloodwork. Glucose numbers that are too high or too low may indicate a health problem that needs attention. A blood glucose level below normal is defined as hypoglycemia; hyperglycemia is blood glucose levels above normal. The body works hard to keep blood glucose levels in a tight range, avoiding wide swings that can affect normal body functions. But some diseases, drugs and physiologic processes can negatively impact the body’s ability to manage blood glucose levels and compromise your pet’s health. Causes of hypoglycemia include:

  • Liver disease
  • Age – young animals are prone to low blood sugar
  • Cancer
  • Sepsis (bacteria in the bloodstream)
  • Extreme exercise (“hunting dog” hypoglycemia)
  • Starvation
  • Xylitol toxicity in dogs (xylitol is a sugar substitute used in sugar-free gum, some peanut butter, and candies)

Causes of hyperglycemia include:

  • Stress-induced in cats
  • Diabetes
  • Acromegaly (excessive growth hormone)
  • Hyperadrenocorticism (Cushing’s Disease)
  • Cancer
  • Corticosteroid use (oral and topical)
  • Hyperthyroidism in cats

Pets with either low or high blood glucose can have signs related to these conditions. Signs of low blood glucose include:

  • Tremors
  • Seizures
  • Incoordination
  • Weakness
  • Aggression
  • Collapse

The only sign of high blood glucose is increased thirst. Other signs are associated with the underlying disease process, such as weight loss in cases of hyperthyroidism in cats, or panting in dogs with Cushing’s disease. The first step in diagnosing a problem with blood glucose is confirming test results. Blood glucose levels can be lowered artificially if blood samples are not separated immediately. Stressed cats can have elevated blood glucose (and most trips to the veterinarians are stressful for cats), so re-testing a cat at another time, or drawing a sample at home is important to rule out stress as a cause for increased glucose. Confirmed abnormal results coupled with clinical signs can help your veterinarian diagnose the underlying cause of either high or low blood glucose. Although some causes of hypo- or hyperglycemia can be challenging to treat (for example, sepsis or cancer) others are much easier. Young dogs and cats are prone to episodes of low blood glucose, but this improves as they mature. Newer insulin preparations have made diabetes easier to treat in both cats and dogs. Advances in the treatment of glandular disorders, such as hyperthyroidism and hyperadrenocorticism, have improved our ability to effectively treat these disorders. Golden retrievers enrolled in Morris Animal Foundation’s Golden Retriever Lifetime Study had their baseline bloodwork evaluated to determine abnormal blood glucose measurements as dogs were beginning the study. As expected so early in the study, the number of dogs having abnormalities was low, with 71 dogs (of 3,044) having blood glucose levels outside the normal range. Seventy dogs had low levels, and one had a high level (but the value was only slightly above normal range). Low blood glucose levels were either noted in young dogs, or were the result of a delay between when the sample was drawn and when the sample was centrifuged and the red blood cells removed resulting in falsely low results. No diseases were reported as the cause for abnormal levels. The Golden Retriever Lifetime Study gives us an unprecedented opportunity to follow multiple variables, including blood glucose, and look for potential risk factors between disease, genetics, environment, nutrition and lifestyle.