Dog - Diabetes Mellitus (DM)

What is diabetes?

Diabetes is a general term referring to disorders characterised by an increased thirst and increased production of weak urine. There are two forms of diabetes in dogs, Diabetes insipidus (Drinking diabetes) and diabetes mellitus (Sugar diabetes).

Diabetes mellitus (DM), is a complex disorder of carbohydrate, fat and protein metabolism caused by the body’s inability to produce or to utilise adequate amounts of insulin produced by specialised cells in the pancreas. Insulin is a hormone that allows glucose to enter the body cells from the bloodstream, providing the essential energy needed for life. DM should not be confused with diabetes Insipidus (DI) which is a very rare condition in dogs.

Are some dogs more prone than others?

Diabetes mellitus commonly affects middle aged, entire (not neutered) bitches.

What is the cause?

In dogs the majority of cases of DM are due to lack of insulin. This hormone is secreted by the Islets of Langerhans in the pancreas. If there is a lack of insulin or the cells of the body become resistant to it, glucose builds up in the blood stream. This is hyperglycaemia. When the amount is too great for the kidneys to cope the excess glucose is passed out into the urine. This is glycosuria.

What causes the lack of insulin?

If the insulin producing cells in the pancreas are destroyed and not replaced, this results in insulin deficiency (hypoinsulinism). This in man is known as Type 1, or Insulin Dependent diabetes mellitus. There are a variety of causes including autoimmune problems and environmental factors such as drugs or infectious agents. Sometimes the cells are destroyed as the result of tumours, injury or chronic inflammation (chronic pancreatitis).

Are there other causes?

• Other diseases of the pancreas can cause DM.
• Certain liver conditions can trigger DM.
• In the bitch DM often occurs shortly after a season when circulating progesterone levels are high. This hormone causes insulin resistance and hence hyperglycaemia.
• Cortisol or treatment with cortisone type drugs can also sometimes cause hyperglycaemia and signs of DM, one of the reasons why sugar diabetes is often associated with Cushing's syndrome.
• Obesity can also lead to insulin resistance resulting in DM.

What are the signs of diabetes?

Weight loss, ravenous appetite, increased thirst and increased urination are classical signs. In addition urinary infections, cataracts and muscle wastage are also often noted. Onset is usually relatively slow over a number of weeks. Left untreated vomiting, poor appetite, depression, coma and death due to dehydration and renal failure can occur.

How is it diagnosed?

The clinical signs discussed play an important part. Blood tests indicating a persistently high level of blood glucose - hyperglycaemia and urine tests indicating the presence of glucose, glycosuria, are important indicators.

Why is hypogylcaemia and glycosuria so important?

Without insulin the cells of the body become starved of energy. They can no longer make use of circulating glucose. As a result the body starts to break down fat and protein to use as an alternative energy source. This results in weight loss and an increase in appetite. The unused glucose accumulates in the bloodstream and finally the kidneys can no longer cope and it spills over into the urine. It has to stay in solution so takes with it vast quantities of the body’s vital fluids. As a result the dog is urinating excessively and to avoid dehydration begins to drink in vast quantities.

What is the treatment?

Basic treatment involves:

• Standardisation of diet and exercise on a daily basis.
• Daily administration of insulin by injection.

Dogs that have had undiagnosed diabetes for some time and have been using body proteins and fats as energy sources may have substances known as ketones circulating in the blood which may be detected in the urine. These dogs often have to be hospitalised and stabilised using intravenous fluids (a drip) together with treatment for any complicating disorders. Treatment for most dogs however is on an outpatient basis since the stress of hospitalisation obviously makes stabilisation more difficult. Attendance at the practice on a daily basis may be necessary for the first few days. During this period we will show you how to inject the insulin. However if at any time you are unsure of the procedure please telephone for advice before administering any insulin.

Can insulin be given by mouth?

Unfortunately insulin is digested in the stomach and small intestine and consequently cannot be administered orally. It has to be given by injection but we will carefully go through the procedure with you until you are confident. It is not as difficult as it appears initially.

Why is it then that some human diabetics do not have to have daily insulin injections and are controlled with tablets?

Type 2, or non insulin dependent DM does occur in people and drugs given by mouth will stimulate the remaining insulin producing beta cells in the pancreas to produce or release sufficient insulin to reduce the amount of glucose circulating in the blood. Unfortunately this type of DM is virtually unknown in dogs.

Is management difficult?

Management of the diabetic dog depends basically upon standardisation. Feeding, exercise and medication including insulin have to be given at the same times each day. Please do not vary the routine without consulting with us.

What happens if I am away at the time my dog should be fed or receive the injections?

If possible try to enlist the help of friends or relatives. If you have difficulty please feel free to discuss it with us, we will do our best to help.

What about holidays? If we take the dog with us will that not cause stress?

The excitement of the impending trip can cause fluctuations in urine glucose values upon which you may depend for the estimation of the insulin required. However we will discuss this very carefully with you and remember we are only a telephone call away if you are having problems.

What happens if I have to go away and cannot take my dog?

Ideally try to enlist the help of a house sitter who can administer the insulin. If this is impossible please discuss it with us and we will try to help by arranging hospitalisation or selecting a suitable nearby boarding kennels that will undertake treatment for you. The stress of strange surroundings without familiar faces can temporarily cause some destabilisation. However we will discuss this with you.

What happens if too much insulin is given?

This will result in hypoglycaemia (too little circulating blood glucose). It commonly occurs if the correct dose of insulin is given but the dog subsequently refuses to eat. It is for this reason that we advise you to feed your dog just before you administer the insulin. The dog is then too busy eating to even notice the tiny injection and at the same time you are assured that the food is being eaten. If no interest is shown in the food, do not give any insulin and telephone us for advice.

Is hypoglycaemia dangerous?

It can be. If due to too much of insulin the first signs are usually that the dog appears tired and almost in a coma. Sugar, honey or glucose can be administered and usually brings about a response in a few minutes. Sugar lumps can be forced into the back of the throat or if dissolved in water the solution can be administered as a medicine. ONLY PUT THINGS IN YOUR DOG'S MOUTH IF IT IS CONSCIOUS. IF YOUR DOG ISN'T CONSCIOUS HE MAY INHALE THE SUGARY SUBSTANCES WHICH CAN CAUSE SEVERE PNEUMONIA

Hypoglycaemia, left untreated, can result in seizures and loss of consciousness. Should this occur, please telephone without delay. This is an emergency.

If you have any concerns or questions please feel free to discuss them with us.

Won’t giving sugar cause hyperglycaemia?

Hyperglycaemia is possible but it will be obvious from the greater amount of glucose apparent on the next urine test and will then be counteracted with the next insulin injection.

Will treatment be expensive?

Initial laboratory tests and stabilisation together with the treatment of any existing ketosis may require hospitalisation and this can be expensive. Once stabilised the cost of insulin and the test kits is reasonable. Regular check ups and blood tests will be necessary.

Once the technique has been mastered, do the majority of owners of diabetic dogs manage to cope?

Initially the thought of daily urine testing, working out insulin dose and then injecting this is pretty daunting. We will take you through the procedure step by step and in addition there are handouts and videos available. Insulin requirements are estimated either from the dog’s water intake or more accurately from determining the quantity of glucose in the urine. Once the diabetes is under control there should only be a minimal amount of glucose in the urine each day. If you have any concerns please feel free to contact us and we will advise.

Once stabilised is my dog likely to be able to lead a normal life?

Yes, although a diabetic dog is obviously a much greater responsibility, provided food, exercise and insulin requirements are carefully controlled there is no reason why the dog should not live a long and happy life.

Is urine glucose the only way for me to monitor my pet's insulin therapy?

No, some vets recommend the use of a hand held glucometer, available from most pharmacies. This can measure the blood glucose concentration from a drop of blood, usually obtained by pricking the pet's ear. This can be useful for at home monitoring. Some animals are not amenable to this type of monitoring, please discuss use of a glucometer with your vet.