Hypoglycemia in dogs, also known as low blood sugar, can be a serious medical condition. If left untreated, it can be fatal if the blood sugar drops too low. It's important for pet owners to know the symptoms and how to recognize when an episode begins. Here are some basics of what hypoglycemia is, why it happens, and how you can prevent and treat it.

What is hypoglycemia in dogs?

Hypoglycemia is a condition that can develop in dogs when their blood sugar levels fall too low. The body needs glucose for energy, and when levels drop too low, the body's cells may not have enough energy to function properly. The normal blood sugar for dogs is 3.5-7mmol/L. Blood glucose levels below 3 mmol/L (<60 mg/dL) are considered hypoglycemic.

The normal physiological maintenance of glucose regulation is achieved by a balance in the secretion of hormones that lower and raise blood sugar. These include insulin to lower blood glucose; glucagon, epinephrine (also known as adrenaline) and cortisol (the stress hormone) to raise blood glucose, in addition to growth hormone. The body gets energy from digesting carbs or breaking down stored glycogen or creating new glucose through glycolysis or gluconeogenesis when needed.

What causes hypoglycemia in dogs?

Hypoglycemia can be caused by exposure to excessive amounts of insulin, excessive glucose consumption by the body, or decreased glucose production.

Excessive insulin

Causes of excessive insulin include insulin overdosage in diabetic patients, insulin produced by a tumour in the pancreas (insulinoma), and xylitol toxicity.

Excessive glucose consumption by the body

Excessive glucose utilization leading to hypoglycemia can occur with severe blood infections (sepsis) or as a part of paraneoplastic syndrome. Paraneoplastic syndrome is an abnormal disorder that is triggered by a cancerous tumour such as lymphoma, hemangiosarcoma and liver cancers for example.

An increase in glucose consumption or depletion of stored glycogen can lead to hypoglycemia in lean, active hunting dogs after extreme exercise.

Decreased glucose production

Hypoglycemia can result from decreased glucose production in toy breeds or newborns, and conditions such as hepatic dysfunction and Addison's disease.

Because newborns have poor muscle glycogen reserves, low body fat stores that provide a substrate for increasing blood glucose, and immature hepatic enzyme systems, hypoglycemia can develop quickly. 

When the liver fails, hypoglycemia can result due to deficient glycogen storage or decreased gluconeogenesis. Hypoglycemia results when approximately 70% of the liver is damaged.

A patient with Addison's disease may develop hypoglycemia because of an increase in peripheral glucose uptake as well as a decrease in hepatic glucose mobilization. In approximately 25% of Addisonian patients, hypoglycemia is present.

What are the clinical signs of hypoglycemia in dogs?

It is not uncommon for patients with hypoglycemia to be asymptomatic. Hypoglycemia can result in a range of clinical signs, depending on the duration, severity, and speed of onset. Possible clinical symptoms include:

  • Anorexia (lack of appetite)
  • Ataxia (lack of coordination)
  • Weakness
  • Vomiting
  • Seizures

How is hypoglycemia in dogs treated?

In an emergency, your veterinarian will recommend an intravenous dextrose solution. Dextrose is essentially concentrated glucose that will quickly cause the blood glucose to rise. Dog owners can apply corn syrup or honey to the animal's oral mucous membranes during a hypoglycemic crisis at home before transporting it to their veterinarian. In a hypoglycemic crisis, oral glucose supplementation is less effective than intravenous dextrose.

For chronic therapy, oral prednisone is often used to manage blood sugar. Prednisone, which is a corticosteroid, will antagonize the effects of insulin, thereby increasing blood glucose.

For small puppies at risk for hypoglycemia, such as chihuahua puppies, feeding small frequent meals throughout the day is important (e.g. 4 meals per day).

What is the prognosis for hypoglycemia in dogs?

Depending on the severity and the underlying causes, the prognosis varies. Patients with an underlying condition that can be identified and successfully treated and who respond to emergency treatment tend to have a good outcome. Hypoglycemia can result in permanent neurological damage when it is severe and prolonged.

What causes low blood sugar in diabetic dogs?

If you notice that your diabetic dog has low blood sugar, then you need to contact your veterinarian to reevaluate your insulin dosage. Chances are, you are giving too much!

Can a dog recover from hypoglycemia?

Yes, a dog can recover from hypoglycemia but it is important to seek veterinary help to properly diagnose and treat the condition. Left untreated, hypoglycemia can lead to seizures or even death. Treatment typically involves administering an intravenous dextrose solution and/or oral prednisone. Depending on the severity and underlying causes of hypoglycemia, the prognosis varies but most dogs do make a full recovery.

Can you give a dog sugar water?

You can but during a hypoglycemic episode, you're better off administering corn syrup or honey onto the gums before bringing your dog to your veterinarian.

What toxins cause hypoglycemia in dogs?

The most common toxin that can cause hypoglycemia in dogs is xylitol, which is a natural sugar found in chewing gum and other "sugar-free" products.

This blog article discussed hypoglycemia, which is a condition that can develop in dogs when their blood sugar levels become too low. Glucose is a type of sugar that is used for energy by the body. When levels of glucose drop too low, the body's cells may not have enough energy to function properly. In dogs, hypoglycemia is most commonly seen in puppies, small breed dogs, and senior dogs. If left untreated, hypoglycemia can lead to seizures or even death if not treated promptly and properly. If you have concerns that your dog may be hypoglycemic, please contact your veterinarian.