Diabetes Mellitus in Dogs Part 1: An Overview

Posted by MyDogDoc on

Diabetes is a lifelong hormonal condition in dogs, which can be fatal if left untreated. .

  • Diabetes in dogs is commonly caused when the dog cannot produce enough insulin, leading to high blood sugar levels

  • Symptoms include drinking and urinating more and weight loss despite a good appetite

  • Most dogs with diabetes can be well managed with twice daily injections of insulin

  • Treatment and management of a diabetic dog is a big commitment, but at the correct dose, most dogs go on to live happy and long lives.

What is Diabetes Mellitus?

Diabetes is a hormonal condition which affects a dog’s blood sugar levels. It usually occurs due to the body not producing enough insulin which is the hormone responsible for controlling the level of sugar (glucose) in their blood.

What is insulin?

Insulin is a hormone which controls the levels of sugar in the blood. The hormone is produced by cells in the pancreas.

After a meal, sugars are absorbed into the bloodstream in the form of glucose. This glucose needs to then be taken up by the cells so it can be used for energy. Insulin is the hormone that makes this happen.

If there is not enough insulin, then the glucose in the blood cannot be taken up by the cells. This results in high levels of glucose building up in the bloodstream, known as hyperglycaemia. The other effect of this is that the cells do not have any glucose which they can turn into energy and so they cannot function normally and effectively “starve”. With time, this results in the dog losing weight despite having a ravenous appetite because they are unable to use the food they are taking in as energy. The body will then start breaking down stores of fat and protein to use for energy instead. The high levels of glucose in the blood spills over into the urine and draws with it large volumes of water. This is seen as increased weeing and increased drinking.

What causes Diabetes?

There are two forms of Diabetes Mellitus.

Type I Diabetes – also known as ‘insulin-dependent diabetes’ is caused when the cells in the pancreas no longer produce enough insulin. This most commonly occurs due to the body attacking its own insulin-producing cells or after an episode of pancreatitis (inflammation of the pancreas). This is the most common form of diabetes seen in dogs.

Type II Diabetes – also known as ‘non-insulin-dependent diabetes’. This is caused when the cells in the body don’t respond to insulin properly and so cannot take up the glucose from the bloodstream and use it. This form is rare in dogs.

What factors make a dog more at risk of developing Diabetes?

  • Age – Middle aged dogs are most commonly affected. Diabetes is more likely diagnosed in those over 8 years.

  • Breed – certain breeds tend to be more prone to developing the disease than others. These include: Border Terriers, West Highland White Terriers, Miniature Schnauzers, Toy Poodles, Terriers, Dachshunds, Beagle, Samoyeds and Bichon Frise.

  • Obesity – dogs which are overweight are more prone to developing the disease

  • Inactivity – dogs that are inactive or do little exercise are more likely to develop insulin resistance, which can lead to diabetes.

  • Neutering Status – entire e.g. not spayed females and castrated males are more likely to suffer from diabetes

  • Other ongoing health conditions – especially those that destroy the cells responsible for producing insulin, such aschronic or repeated episodes of pancreatitis, autoimmune diseases and Cushing’s Disease.

  • Previous steroid medication – if your dog has been on long-term steroid medication, this can increase their risk of developing diabetes later on.

What are the symptoms?

  • Increased thirst

  • Increased urination (peeing more)

  • Increased appetite

  • Increased weight loss

  • Low energy (lethargy or tiredness)

  • Cataracts (eyes appear cloudy)

  • Repeated urine infections (eg cystitis)

If left untreated, diabetes can prove life threatening. When the body cannot produce enough energy from glucose, it starts to break down fat as an energy source. This breakdown of fats produces ketones. Ketones build up in the bloodstream and result in a condition called Diabetic Ketoacidosis (DKA), which can be fatal.

The symptoms of DKA include:

  • Vomiting

  • Diarrhoea

  • Lack of appetite

  • Lack of energy

  • Weakness

  • Appearing unsteady as if drunk

  • Collapse

  • Sweet-smelling breath

If your dog is diabetic and you notice any of these symptoms, contact your vet immediately as this is an emergency.

How is Diabetes diagnosed?

Diabetes Mellitus is diagnosed based on the symptoms, a persistently high level of glucose in the blood and the presence of glucose in the urine.

Your vet will want to take bloods to check your dog’s blood sugar levels and will also need a urine sample so they can test the urine for the presence of glucose.


This is by twice daily injections of the hormone insulin. This is given under the dog’s skin by the owner at home but don’t worry! Owners receive training from their vets and vet nurses on how to do this, so you will be supported every step of the way. The needle is very small, and most dogs barely notice the injections at all!

It is important to keep meals at the same times each day, and to always feed the same amount and type of food. It is also essential to not feed your dog in between meals especially with high sugar treats as this can lead to a rapid increase in blood glucose.

Likewise, keeping exercise to a set amount each day is important as exercise uses up blood sugars.


This is very important, especially in the early stages of starting insulin treatment, to ensure that your dog is on the correct dose of insulin and it’s blood sugar levels are not falling too low (hypoglycaemia). Your vet will want to regularly measure the levels of glucose in your dog’s blood and urine. They may also teach you to do this at home.

Signs of low blood sugar include:

  • Unsteadiness or dizziness

  • Weakness

  • Being lethargic or groggy

  • Collapse

  • Seizures

If you notice any of these signs, it is important you call your vet immediately as this is an emergency.


Whilst treatment is not a cure and your dog will require lifelong medication, once stable, treatment is usually very effective at controlling the condition. Many dogs go on to live long and happy lives, but it is important to understand that treating and managing a diabetic dog takes a lot of dedication, hard work, a strict routine and regular trips to the vet.

If you have a diabetic dog and would like any further advice or support, one of the vets at MyDogDoc would be happy to help.

Blood Glucose curve Cataracts Diabetes Diabetes diagnosis Diabetes Mellitus Diabetes symptoms Diabetes treatment Diabetic Diabetic Ketoacidosis Dog Drinking more Eating more Fructosamine Glucose Health Insulin Ketones Losing weight Sugar levels Urinating more

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