Diabetes in Dogs - Factsheet

Diabetes mellitus (common diabetes) is a condition in which glucose sugar is passed in the urine. This happens when there is too much of the glucose in the blood and the excess is then voided by the kidneys.

Glucose is the substance that provides the energy in a cdog. It comes from the food, most notably from carbohydrate, but it can also be produced by the conversion of fat. After a meal there is a large surge of this glucose as it is absorbed in the bowel, and this is stored in the body, under the control of a hormone called insulin.

In diabetes this hormone is either faulty or deficient. This has two effects:

The glucose absorbed from the bowel cannot be stored and is wasted in the urine
Between meals the blood glucose levels drop and the body's reserves (fat depots) have to be mobilised, so the cat loses weight.

DIAGNOSIS

A common sign is an increase in thirst and appetite. Weight loss is usually noted, unless there are other illnesses going on at the same time. Blood samples and urine samples show very high levels of glucose and the diagnosis is confirmed with further blood tests.

TREATMENT

The aim is to replace the missing insulin, so that the body can regulate its glucose levels properly. Because insulin is a protein it would be broken down by the digestive enzymes if given by mouth so it has to be injected.

To determine how much is needed on a daily basis requires blood sampling, but this becomes inconvenient and costly. Therefore we rely on urine samples instead. However, these only record the glucose once it has reached the urine, and could therefore reflect a level several hours ago. A further problem is that if the urine contains no glucose we do not know how much is in the blood, and it could be too little. (q.v.) so we aim to have 1/10 % showing on the monitoring sticks (keto-diastix).

Dogs usually become stable with once daily injections of insulin but sometimes twice daily dosing is necessary.

FEEDING

Food must be regular and the quantities should be constant so that we know exactly how much energy is being given and thus can calculate how much insulin is needed. Treats and titbits contain energy and will need more insulin. Conversely missing a meal means that less of the injection will be needed. The meals should be at set times during the day with half being given in the morning and half about eight hours later.

It is important to make sure they are eaten before any insulin is injected.

The aim is to provide a regular number of calories a day, and at regular times.

The best foods are those with complex carbohydrates in them, and these include high fibre diets since they release their glucose more evenly and over a longer time period. We will advise you on which food is the most suitable.

Avoid sweet foods and those high in fat. A moderate reduction in protein intake will help the kidneys and reduce the chance of complications like cystitis.

PROCEDURE

Feed the dog. Make sure the meal is eaten.
Inject the correct amount of insulin, based on the last urine sample, about 30 minutes after the meal. Keep the insulin in the fridge so that it doesn't go off.
Collect urine samples daily and measure the amount of glucose coming through using the keto-diastix. The first urine sample in the morning is not ideal as it measures a long time period of the glucose and not the immediate need. The best time to collect the urine for analysis is 8-12 hours after the insulin.
Meals and treats should be given at the same time each day, and use the same quantity.

CALCULATING THE DOSE OF INSULIN

The general rules are:

0% - drop the insulin by 2 units
¼% - give the same amount as before
¼ - ½% - give 1 unit more than before
> ½% - give 1-2 units more

Initially, the amount of insulin will be small, and the urine will read 2%. The amount of insulin injection that is needed will be increased until the glucose reading is 1%. There will then be a few days when the amount injected remains the same since the body has to adapt to the drug.

OVERDOSE OF INSULIN

This can be prevented most of the time by careful monitoring. However be aware that if a dog isn't eating or has diarrhoea then there will be fewer calories being absorbed. If in doubt either reduce or miss the next dose of insulin. It is less of a problem for there to be too much glucose around than too little.

Signs of an overdose include a dog that is dull and lethargic. The dog may become wobbly and unable to stand, may become very vocal and may salivate. If left untreated the dog will convulse and go into a coma. This is known as becoming 'hypo' (hypoglycaemic).

First aid: feed glucose water or honey water if the dog can still swallow. Repeat this every few minutes until the dog comes round and appears normal. Miss the next dose of insulin.

In later stages, when the swallowing reflex has gone, the dog will need an intravenous injection of glucose. There is not much time to act so don't delay.

Any hint of an overdose should be reported to the veterinary surgeon immediately, regardless of it being day or night.