Hypoglycaemia (Low Blood Sugar)

Top Tip

Keep glucose syrup or honey on hand to give your dog if you notice:

Weakness
Wobbliness
Tremors
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Quick action can save your dog’s life during a hypoglycaemic episode.

Hypoglycaemia means your dog’s blood sugar has dropped too low. It can happen if too much insulin is given, if meals are missed, or after extra exercise. Low blood sugar is an emergency, so it’s important to recognise the signs quickly and know how to respond.

What is Hypoglycaemia?

Hypoglycaemia (low blood sugar) is when the glucose level in the blood drops below 3.3 mmol/L (60 mg/dL). This situation is really dangerous because cells in the brain and nervous system depend on glucose as their main fuel source and take it up directly from the blood without needing insulin. If blood glucose levels drop too low, there’s not enough of a ‘push’ to move glucose from the blood into these cells and the cells quickly run out energy leading to confusion, seizures, and even death in severe cases.

What Causes Hypoglycaemia?

The three most common reasons why diabetic dogs get hypoglycaemia are:

The dog was given too much insulin. This can happen when someone mistakenly draws up and administers 20 units of insulin instead of 12 units, two people in the same household give the insulin dose, someone mistakenly uses a U-40 syringe with U-100 insulin, or the dose adjustment was too high.

The dog didn’t have enough food around the time of the insulin injection. This can happen either because it wasn’t feeling hungry enough to eat or it vomited the food out after eating. Without enough food, there wasn’t the usual rise in blood sugar to balance out the usual amount of insulin given.

The dog was exercised too heavily. During physical activity, muscles use a lot more glucose for energy. In diabetic dogs receiving insulin, the insulin is still active during exercise and can push glucose into the cells faster than the body can replace it by breaking down glycogen stores in the muscle and liver.

What Does Hypoglycaemia Look Like?

If your dog’s blood sugar drops too low because they received too much insulin compared to how much food they ate, signs of hypoglycaemia can show up anywhere from 30 minutes to 8 hours after the injection. The exact timing depends on the type and dose of insulin, but signs often appear around the time the insulin has its strongest effect — usually about 5 to 8 hours after the injection. Dogs that get hypoglycaemia during exercise will usually show clinical signs immediately.

When the hypoglycaemia is still relatively mild in the early stages, you may notice:

Tiredness or weakness
Wobbliness or unsteadiness
Shivering or tremors
Disorientation or confusion

Because dogs often sleep a lot during the day, the early signs of tiredness or weakness may be difficult to spot. As long as levels don’t go too low, the blood glucose will generally start going back up to normal within a few hours as the insulin wears off.

If the hypoglycaemia becomes more severe, you may start to see:

Unconsciousness
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Seizures
Coma
Death

*** This is a medical emergency and your dog needs to be seen by a veterinarian immediately to receive an infusion of glucose directly into the blood. ***

How do we Treat Hypoglycaemia?

If your dog seems weak or unsteady and you can safely check blood glucose at home, do so. If you can’t check levels — or if you do check and the blood glucose levels are low — your dog will need glucose right away.

Glucose syrup is a good option and is dosed at 1.5 mls per kg (equivalent of 1 tablespoon per 10 kg or 1 teaspoon per 3 kg).

In New Zealand, you can find Queen Glucose Syrup 500g in the baking aisle of Woolworths or New World for ~$6.50 per bottle. Your veterinarian can give you some plastic syringes to have on hand for drawing up the right amount in an emergency. You can also ask for some syringe caps to make up dosing syringes that you can carry with you on walks or during other periods of exercise.

Glucose Syrup Dose Calculator

Dog’s weight

kg lb

Honey can be used as an alternative if glucose syrup isn’t available, but the response may be a bit less predictable. That’s because honey contains a mix of sugars — mainly glucose and fructose — and the exact amounts can vary depending on the type of honey. While glucose is absorbed quickly and helps raise blood sugar fast, fructose takes longer for the body to process and doesn’t have the same immediate effect.

If your dog is awake and able to swallow, you can syringe it directly into the mouth or try to rub it over the gums.

For dogs that are unconscious, having difficulty swallowing, or having seizures, it can be dangerous to syringe liquid or food directly into their mouth because it can go down into the lungs instead of the stomach and cause your dog to get aspiration pneumonia. Instead, rub the glucose syrup over the gums or place under the tongue if it safe for you to do so without getting bitten.

Most hypoglycaemic dogs show improvement within 10–15 minutes of receiving glucose. Once your dog is awake, feed it a small meal, which will provide glucose over a longer time period. If there’s no change, or symptoms return, treat it as an emergency and contact your vet immediately.

Once your dog is stable, it is important to figure out why the episode happened to help you keep your dog safe and prevent it from happening again.

How do we Prevent Hypoglycaemia?

There are simple steps you can take to lower the risk of hypoglycaemic episodes in your dog:

Make sure everyone who will be administering insulin to your dog knows how to draw up the correct volume.
If you are using syringes rather than a pen to give insulin injections, always make sure the syringes are the correct size for your insulin type (U40 or U100) .
Keep a medication log that everyone can see or access to record when insulin doses are given.
If your dog is a picky eater or seems a little unwell, wait until after they have finished their meal before giving the insulin injection and ideally keep an eye on them for the next hour to make sure they don’t vomit.
Any time you increase the insulin dose, monitor your dog closely for the next 12 hours for signs of hypoglycaemia and/or perform a blood glucose curve to make sure your dog is not getting hypoglycaemic during the peak activity.
If you are taking your dog out for exercise, take a diabetes pack with you that contains a blood glucose monitor (if you have one), a pre-loaded syringe with glucose syrup, and a small amount of their regular food that can be given as a snack.