Jack Russell dog

The first sign that your dog is diabetic is usually an increase in thirst and urination.

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Diabetes in dogs: symptoms, causes and treatment

By Dr. Katy Ellison MA VetMB MRCVS Veterinarian

Updated on the

With the right treatment, a dog with diabetes can expect to have a normal life expectancy.

Diabetes is one of the most common hormonal diseases in dogs. It can affect any age of dog, although peak incidence for signs developing is between 7 and 10 years old. It tends to be more common in female dogs then males, and certain breeds are more at risk than others. The good news is that treatment is usually very successful and dogs with diabetes that is well controlled can expect to have a normal life expectancy and quality of life.  

What are the symptoms of diabetes in a dog?

The classic symptoms or clinical signs of diabetes mellitus in dogs are an increase in thirst (polydipsia), an increase in urination (polyuria), an increase in appetite (polyphagia) and weight loss. Often the first sign to develop is the increase in thirst and you may notice that you are having to fill up your dog’s water bowl more frequently than you used to. If diabetes is left untreated, symptoms may progress to lethargy, inappetance, vomiting and diarrhoea. Cataracts are one of the most common complications of diabetes in dogs. They tend to make the eyes appear cloudy and will eventually cause blindness.

What are the causes of diabetes in a dog?

Diabetes in dogs is generally caused by a deficiency of insulin. Insulin is a hormone that is produced by the pancreas that enables your dog to use the glucose (sugar) from their food to provide energy or to store it for future use. Without insulin, it is not possible to control blood glucose levels so hyperglycaemia (high-blood glucose) will result. In most dogs with diabetes the cells in the pancreas responsible for insulin production (pancreatic beta cells) are progressively destroyed resulting in a deficiency of insulin. The cause of this beta cell destruction is unknown at present, although there are a number of theories, including immune-mediated disease (an abnormal immune response).

In a small percentage of dogs, diabetes will be caused by insulin resistance. In other words there is enough insulin being produced by the pancreas but the dog’s body has become resistant to the insulin. This is normally caused by another hormone antagonising (working against) insulin, for example cortisol in dogs with Cushing’s disease or increased levels of certain reproductive hormones in female dogs that are pregnant or in season. Obesity is also linked to insulin resistance.

How is diabetes in a dog diagnosed?

The first step in reaching a diagnosis is to arrange an appointment with a veterinary surgeon. They will ask you for a thorough history and it is often a good idea to write down any changes you have noticed before your visit – it is all too easy to forget important information when you are worried about your pet. One particularly useful piece of information is how much water your dog is drinking over a 24-hour period. This is known as your dog’s 24-hour water consumption and it is very simple to measure, but provides your veterinary surgeon with really useful information.  

Your dog will be thoroughly examined and once information from the history and clinical examination has been considered, the veterinary surgeon will suggest performing some blood tests. Blood glucose will be checked and, if your dog is diabetic, their blood glucose levels will be high. There are other causes of hyperglycaemia (high blood sugar) including stress, so your veterinary surgeon may suggest a fructosamine test. Fructosamine can be thought of as an average blood glucose reading over the previous two weeks and, if high, confirms a diagnosis of diabetes. Full blood biochemistry and haematology tests are also advisable to check general organ function and screen for any other underlying disease.

What treatment is there for diabetes in dogs?

Treating a dog with diabetes may seem a bit daunting at first because in almost all cases you will be required to inject your pet twice a day with insulin. Many owners worry about whether they will be up to the job but within a very short time, injecting your dog will become part of your daily routine and you will wonder what you were worrying about. To start their insulin injections your dog will probably spend a day at the veterinary practice and then you will continue the treatment at home. Fairly frequent blood glucose tests will be done in the first few weeks until your dog’s blood glucose is stabilised. Be patient because it can take some time to get the insulin dose just right for your dog.

How do you know if your dog has diabetes?

The first sign that your dog is diabetic is usually an increase in thirst and urination. They will often lose weight despite the fact that they are eating more than normal.  If you notice any of these changes in your dog, you should arrange an appointment with a veterinary surgeon. When you attend the practice, it may be helpful if you take a sample of your dog’s urine with you.

How long do dogs live after being diagnosed with diabetes?

There is no reason why a diabetic dog should not have a normal life expectancy with a good quality of life. Although a treatment regime involving twice-daily insulin injections may seem a challenging prospect, with appropriate monitoring and dose adjustments as required, it is usually very successful.  

How do you treat diabetes in dogs?

Diabetes in dogs is treated with insulin injections twice daily, usually 12 hours apart. The veterinary surgeon will calculate an appropriate starting dose of insulin based on your dog’s body weight. The first dose will usually be given at the veterinary surgery and your dog will be closely monitored with blood glucose measurements every few hours to make sure their blood glucose levels are not dropping too low (hypoglycaemia). You will then be able to continue treatment at home. After five to seven days further blood glucose measurements may be taken and the dose of insulin adjusted if required. It often takes several weeks to get the insulin dose perfect for your dog, but once things are stable, the frequency of vet visits will be able to be reduced significantly.

There are other lifestyle adjustments that will help in the management of your dog’s diabetes. Keeping to the same daily routine is particularly important, so try to keep their exercise levels similar every day. You will probably need to adjust their feeding regime as well, so that their food is the same every day. This means the same amount of the same type of food fed at the same time every day. Usually it will be advised that your dog is fed twice a day close to the time of their injections. The exact timing of meals and the best food for your dog is something that you should discuss with a veterinary surgeon.

How much does it cost to treat a dog with diabetes?

It is very difficult to give an accurate idea of cost of diabetes treatment in dogs, because there are so many different factors to take into account. A small breed dog with no other health problems that is straightforward to stabilise will be less costly to treat than a large breed dog with a complicating factor, such as Cushing’s disease for example. So costs can vary greatly and it is best to speak to a veterinary surgeon, who should be able to give an estimate of expected costs.

Are diabetic dogs in pain?

Diabetes is not a painful condition. As such, if you think that your dog is in pain, you should make an appointment with a veterinary surgeon as soon as possible. It is very unlikely that diabetes is the cause.

What happens if you don't treat a dog with diabetes?

If diabetes is untreated, your dog’s general health and quality of life may decline gradually over the course of several weeks or months. They will progressively lose weight and their thirst will continue to increase, frequently resulting in urinary accidents in the house. Sometimes diabetic dogs will develop a life-threatening condition called diabetic ketoacidosis. The signs of ketoacidosis include vomiting and diarrhoea, profound lethargy and a characteristic smell of acetone (often compared to the smell of pear drops) on the breath. Dogs can die very quickly from ketoacidosis and untreated diabetics are at a high risk for developing this complication.

Do diabetic dogs sleep a lot?

Diabetic dogs that are receiving twice-daily insulin injections and are well managed should have a normal quality of life and so they should not sleep any more than a dog that is not diabetic. If your diabetic dog is sleeping more than normal, it may be a sign that for some reason their blood sugar levels are not as well controlled as they should be, and this should be investigated by a veterinary surgeon.

How did my dog get diabetes?

The majority of diabetic dogs are insulin deficient, in other words their pancreas is not producing enough insulin. Without insulin, glucose from carbohydrates in your dog’s diet cannot be utilised. The cause of this lack of insulin production is usually not known but may be caused by an abnormal immune response attacking the pancreas. The end result is always the same, namely that your dog will require insulin injections twice daily for the rest of their lives to make up for this deficiency.

Some dogs will be what is known as insulin resistant, so their pancreas produces insulin but something (usually another hormone) antagonises, or works against it, preventing it doing its job. The commonest hormones that cause this antagonism are cortisol (high levels are seen in a condition called Cushing’s disease), or some of the reproductive hormones such as those involved in pregnancy. Obesity, while not the sole cause of diabetes in dogs, will contribute to insulin resistance, so make sure you keep your dog slim.

Some breeds of dog have a higher risk of developing diabetes, but we often do not know why one dog develops diabetes and another dog does not. In the majority of cases there will be nothing that you could have done to prevent this condition developing.

Can you reverse diabetes in dogs?

Diabetes in dogs is not usually reversible because the majority of cases are caused by destruction of the pancreatic beta cells that are responsible for producing insulin. Unfortunately these cells cannot regenerate, so diabetes cannot be reversed.

In a minority of cases diabetes will be caused by insulin resistance and the pancreatic cells retain their ability to produce insulin. In some of these insulin resistant cases, such as diabetes associated with heat in female dogs, the condition can be reversed, in this case by spaying. It must be stressed though that being able to reverse diabetes is the exception rather than the rule, and most dogs will require lifelong insulin injections to manage the disease.

What breeds of dogs are prone to diabetes?

All breeds of dog can develop diabetes. Having said that, certain breeds do seem to have a higher incidence of the condition, including: miniature poodles, Tibetan terriers, Cairn terriers, Beagles, Samoyeds and Labradors. Some breeds, such as Boxers, seem to have a lower than average incidence of the disease. This suggests that there are genetic factors that determine susceptibility to diabetes.

Can my dog get diabetes from Cushing’s disease?

Cushing’s disease (hyperadrenocorticism) is a hormonal disease characterised by excessive levels of the stress hormone cortisol. It is caused either by a tumour in the pituitary gland of the brain (pituitary dependent hyperadrenocorticism) or an adrenal gland tumour (adrenal dependent hyperadrenocorticism). The classic signs of Cushing’s disease are an increase in thirst (polydipsia), an increase in appetite (polyphagia), a pot-bellied appearance and, frequently, skin and coat changes. The signs can be very varied because cortisol has wide-ranging effects within the body.

High circulating levels of cortisol can cause a condition known as insulin resistance. Insulin is a hormone that enables glucose from the diet to be utilised. When a dog is insulin-resistant, there may be adequate levels of insulin but the ability of the body to respond to insulin is impaired and, as a result, levels of glucose within the blood become elevated (hyperglycaemia) and diabetes results.

In a diabetic dog that is proving difficult to stabilise on insulin or requires very high doses of insulin, the possibility of insulin resistance should be investigated. Cushing’s disease is one of the more common causes of insulin resistance and should be ruled in or out at an early stage in investigations.

What types of diabetes are there in dogs?

When we talk about diabetes, we generally mean diabetes mellitus or “sugar diabetes”. Normally the pancreas produces a hormone called insulin that enables the body to utilise glucose (sugar) from food. In a dog affected by diabetes mellitus, they are unable to utilise the sugar that comes from carbohydrates in their diet, either because of a lack of insulin production by the pancreas or because there is insulin resistance present caused by another hormone working against or antagonising the insulin.

There is another type of diabetes that is less common called diabetes insipidus. Normally a hormone called antidiuretic hormone (ADH) helps the kidneys to regulate the amount of fluid that is lost in the urine. In diabetes insipidus there is either a deficiency of ADH or the kidneys are unable to respond to ADH. The end result is that large volumes of very dilute urine are produced. Diabetes insipidus is relatively rare.

What diet should I feed my dog with diabetes?

If your dog has been diagnosed with diabetes, there will need to be adjustments made to their diet and feeding regime. The key point is that you keep to the same routine every day. Opinions differ in terms of the right time to feed your dog. One theory is that you should feed your dog prior to giving them their insulin injection to make sure that they have eaten, so reducing the risk of their blood sugar dropping too low (hypoglycaemia) after insulin administration. This is sensible advice.

Yet in reality it is best that you discuss with a veterinary surgeon what works for you and your dog. For example, if you inject your dog while they are eating they may be less likely to notice the injection and that will make the whole process less stressful for you and your dog. Do not make any changes to your dog’s feeding regime without first discussing it with the veterinary surgeon.

You may need to change the type of food that you give your dog. Just as with human diabetics you need to restrict the amount of certain carbohydrates that you feed. There are prescription diabetic diets that are ideally formulated for diabetic dogs and you should discuss with a veterinary surgeon which one would be most suitable. Home-prepared diets are rarely nutritionally balanced, especially when you add complicating factors such as diabetes.

When should I see a vet?

The first symptoms of diabetes that most owners notice are an increase in thirst and urination. If you have noticed these changes, contact a vet at the earliest opportunity. The sooner a diagnosis is made, the sooner your dog can be started on appropriate treatment. Do not wait until your dog seems obviously unwell, because it reduces the chances of successfully treating your dog’s diabetes.

If your dog has already been diagnosed with diabetes and is receiving insulin injections, hopefully they will be able to live a normal life with relatively few problems. But if they appear unwell in any way, seek veterinary advice straight away, because an unwell diabetic can deteriorate quite quickly without appropriate treatment.

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