Diabetes in Dogs and Cats

What is Diabetes?

Diabetes mellitus occurs when the pancreas does not produce enough insulin to properly regulate blood glucose (sugar) levels.  The cells of the body rely on glucose for energy.  Without insulin, glucose in the bloodstream cannot be passed into cells, which means the glucose level in the blood is high but the body’s cells are effectively starving. 

If cells cannot obtain their energy from glucose, they use another type of energy source called ketones, which are produced from the breakdown of fat.  High levels of ketones can make our pets quite unwell, common symptoms being lethargy/depression, vomiting and severe dehydration. This is called Diabetic Ketoacidosis and requires urgent and intensive treatment in hospital.  

What are the Signs my Pet may have Diabetes?

1. Eating more/ravenous appetite: The low glucose level in the cells (despite it being high in the blood) makes the body think it is hungry. As the animal cannot get the energy usually supplied by glucose it tries to compensate for this by eating a lot more food.

2. Drinking excessively: There is so much glucose in the blood that the kidneys are overwhelmed and a lot of glucose is passed into the urine.  This glucose pulls water out with it, leading to increased urination and consequently increased thirst.

3. Weight loss: Despite the fact that diabetics often eat more, they will start to lose weight as most of the energy from the food cannot be utilised by the cells in the body.

 4. Urinary Tract infections: All the glucose in the urine makes the bladder an excellent place for bacteria to grow.

 5. Cataracts: In dogs, high amounts of sugars can enter the lens causing rapid cataract formation. The lens of the cats is different and we don't see diabetic cataracts in this species.

6.  Diabetic Keto-acidosis (DKA): A severe illness where the animal stops eating, seems reluctant to move, may start vomiting and seem subdued/depressed.  This can occur if diabetes mellitus is left untreated or the animal develops another disease or problem (such as running out of water on a hot day, developing a urinary tract infection or even just having an episode of gastro-enteritis). If left untreated DKA can lead to coma and death.

Diagnosis of Diabetes in Pets

Your vet can diagnose diabetes mellitus by looking at a blood and urine sample and finding excess glucose in both.  Ketones may also be found in the urine. Usually a full blood screen and urine analysis are done at this time to assess general health and pick up any other complicating issues.  

Treatment of Diabetes in Pets

If your pet has stopped eating and has a build-up of ketones in the blood (Diabetic Ketoacidosis), he/she may need to be hospitalised for intensive treatment with intravenous fluids and insulin therapy until they are stable.

Once an animal is stable, eating and drinking normally, treatment involves insulin injections as well as dietary changes and a set exercise routine if possible.  Insulin injections under the skin are usually required twice a day and done as close to 12 hours apart as possible.  Although giving injections can be a little overwhelming at first, it becomes easier with practice and soon becomes part of the regular household routine. Your vet will explain how much insulin to use and will be able to show you how to give these injections at home. If you're not sure that your pet got the entire dose of insulin, it is best NOT to repeat the dose, but give the next dose as scheduled.

Insulin injections are usually given just under the skin at the back of the neck, between the shoulder blades. Most dogs and cats do not even notice the injection. It is best to offer a meal first, and when they have eaten and/or are eating, then give the injection. It can be dangerous to give an insulin dose to your cat or dog if they have gone off their food and do not eat.  Usually dogs should only be fed morning and night.  No additional food should be offered in between and the meals should be of equal size.  However cats, (and some dogs), may prefer a “grazing” pattern of eating with food available at all times. Your vet will advise you on the most appropriate food to offer and when.

Twice daily injections of insulin have to be continued for the life of all diabetic dogs. Cats may not always require insulin therapy and can sometimes be managed on other medications. In cats there is also the potential for the diabetes to resolve (“remission”) if the pancreas is able to improve its insulin secreting ability.

The amount and type of insulin can vary – as can the type of syringe or pen used. Make sure that you always obtain the correct syringes from your vet for the insulin that you are using.  We are more than happy to safely dispose of your used syringes here at the vet clinic.

All animals are different and it can take time as well as insulin dosage adjustments to stabilise their diabetes. Initially regular checks are required to monitor the blood glucose levels, and therefore the dose of insulin that is needed.  Often these checks will initially be every 2 to 4 weeks and will require that your pet stays a day in hospital for regular blood glucose testing (known as a blood glucose curve) to occur.

Managing and Monitoring Your Diabetic Pet at Home

Often it is best to start a diary for a diabetic at home. This makes it easier to monitor not only how much they are eating and drinking but also if they are gaining or losing any weight. Urine reaction test strips can also be used (available from your vet or a chemist) if necessary to monitor the levels of glucose and ketones in their urine.


 A diabetic animal should have a source of clean water available at all times. The normal water intake for a dog or cat is around 60 to 100ml per kg of body weight in a day. This will vary with temperature and amount of exercise, but excessive drinking is a sign of unstable diabetes. Initially the water intake may have to be measured daily. Once a diabetic is stable checks once or twice a month may be adequate.


Regulation of both exercise and diet help all diabetic animals.  Usually we aim to feed 50- 70kcals/kg/day divided into two meals. If your animal is underweight this may be increased – if overweight it may be decreased.

For cats, a low carbohydrate, high protein diet is ideal. Your veterinarian can recommend appropriate diets for your pet. Treats and any fatty foods should be avoided. If it is not possible to change your pet’s diet then regulation will have to be worked out around whatever your pet will eat.


The initial dose of insulin your pet goes home on is unlikely to be the dose they stay on forever. Sometimes a lot of fine-tuning is required to get the dose of insulin just right for your pet. Not getting enough insulin will result in hyperglycaemia (high blood glucose). If this happens your animal will drink excessively, be very hungry and have a lot of glucose or even ketones present in the urine.  You should never change your pet’s insulin dose without first consulting your Veterinarian.

Getting too much insulin, not enough food or over exercising can result in hypoglycaemia (ow blood glucose). Hypoglycaemia can be life threatening and the symptoms of this are varied but can include falling over, appearing very ‘spaced out’, shaking, lethargy or reluctance to move.  It will eventually progress to seizures. If you think that your pet may be hypoglycaemic, put some honey or glucose syrup on your pet’s gums and then see a vet as soon as possible.

It is important to handle your insulin carefully.  Insulin molecules are fragile and shaking the bottle can result in damage to the insulin and render it ineffective. Roll or gentle invert your insulin bottle to mix the insulin prior to drawing up the insulin dose.  It is also important to keep the insulin in the fridge and transport it in a cool pack if travelling longer distances.

Urine monitoring

Sometimes your veterinarian may ask you to monitor the amount of glucose and ketones in your pets urine.  This can be done via glucose and ketone urine test strips available from most chemists and your vet.  Initially you may need to do this every day to start with and then on a weekly basis if necessary.

Ketones: We always aim for negative ketones. The presence of any ketones in the urine could mean your pet is becoming unstable and you should phone your vet clinic straight away.

Glucose: To start with we will not be too worried about how much glucose there is in the urine. A negative glucose means that your pet may be getting too much insulin and be at risk of a hypoglycaemic (low blood glucose) episode. Eventually we would like to see the glucose in the 1+ or 2+ range.

When to Contact Your Vet

Your vet will advise you regarding how often a recheck is required and whether any adjustments need to be made to your pets insulin dose. However, you should ring your vet or bring your pet in for a recheck if you note any of the following:

• Your pet seems to feel ill or is not eating.

• Your pet is losing weight but still seems to have a ravenous appetite.

• Your pet seems to be drinking or urinating excessively.

• Ketones are present in the urine for three days in a row.

• Your pet becomes disorientated or groggy - If your pet appears wobbly, ‘spaced out’ or appears ‘drunk’, the blood sugar level may have dropped too low.  First try to get your pet to eat. If they will not eat place a small amount of glucose syrup or honey on their gums and then contact your veterinarian immediately.

We can be contacted on 97274004.

Download this guide as a pdf