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Guidelines for Management of Diabetes Mellitus in Dogs and Cats

Diabetes Mellitus (DM) is a common endocrine disease found in canine and feline medicine.

It is caused by a deficiency of insulin. Insulin is normally made in the pancreas. Cells in the body cannot absorb glucose without insulin being present, therefore we get a pet with high blood glucose levels and weight loss (due to the tissues of the body starving).

Symptoms of Diabetes

  • Excessive thirst
  • Excessive urination
  • Excessive appetite
  • Weight loss
  • Cataracts (in dogs, not cats)

If your pet has any of the above symptoms, your vet will initially want to run a full panel of bloods to check liver and kidney function, as well as blood glucose levels. A urine sample will most likely be tested as well. Diabetes can usually be diagnosed from these tests. Sometimes an extra blood sample will be sent the laboratory to confirm if there are borderline results.

The difference between cats and dogs with diabetes

Dogs: Virtually all dogs have insulin-dependent diabetes. It is permanent. You will need to inject insulin for the rest of their life.

Cats: Most cats have non-insulin-dependent diabetes, which is similar to type II human diabetes. For some cats, the diabetes can resolve if the pancreas improves its ability to secrete insulin, so the diabetes may not be permanent. You will need to give insulin injections initially, if you want a chance of your cat going into remission. Some diabetic cats (as much as 25%) have severe hormone issues which can make them resistant to insulin and therefore difficult to manage.

Treatment of diabetes: giving insulin by injection

You will need to learn to give injections, which can be very daunting initially. We are here to guide you. Please ask any questions that come to mind. If you are not comfortable at any stage we are happy to spend time with you until you are satisfied that you can give the injections.

Most pets require insulin injections twice a day, approximately 12 hours apart, following a meal.

We usually use Caninsulin for dogs, which comes in a small glass bottle which must be kept upright in the fridge. Gently invert the bottle a few times to ensure it is uniform in appearance. You will need to draw the correct dosage into a syringe before injecting it into your dog. Take care to ensure no air bubbles are in the syringe as this will affect the dose. Caninsulin must be kept in its original packaging in a refrigerator. Keep the used needles and syringes away from children and bring them back to the vet clinic at your convenience for us to dispose of them. Ideally, a vial of caninsulin should be disposed of after 28 days, even if there is still insulin left.

Your dog’s starting dose of Caninsulin is ____________ IU twice daily.

We use a different type of insulin in cats, Lantus glargine. This comes in a pen format. You twist the end to “dial up” the correct dose before injecting your cat. We recommend always injecting 1 unit over the sink before dialing the correct dose, as often a wee air bubble can sit in the hub of the needle. Needles need to be changed regularly so they don’t go blunt. The pen is refrigerated only until it is opened. Once started, the pen should be kept at room temperature. Please keep the used needles in a safe place away from small children and bring them to the clinic at your convenience for us to dispose of them. Ideally, pens should be discarded after 28 days, even if there is insulin still left.

Your cat’s starting dose of Lantus glargine is _____________ units twice daily.

Overdose of insulin is potentially an emergency, so if you are unsure if you gave it correctly, it is best not to repeat the dose, wait 12 hours and continue as normal.

Never change the dose unless advised by your vet. We need to do a “glucose curve” or “spot check” before we consider the dose changes. 

A glucose curve is when we admit your pet to the hospital for a day. We take regular blood samples (every 1-2 hours) so we can track your pet’s response to the insulin injection. You will feed and inject your pet at the normal time that morning and drop him/her off between 7.30-9am. We need to do this quite regularly initially (every 2-3 weeks) until we find a dose that keeps your pet’s glucose levels stable. Then we usually see them every 3-6 months thereafter to ensure no tweaks need to be made.

Once your pet is stable, or if they don’t cope being in hospital for a whole day, we often opt for a midday “spot check” of glucose that can be done in a consult. The blood glucose level is often at its lowest point midway between the two insulin injections. We can make decisions for dose adjustment based on this number as well.

Diet and Feeding

Regulation is usually established whatever the animal is eating, but there are some diets which do help with control of Diabetes Mellitus.

For dogs, high-fibre diets help slow the absorption of sugars and maintain a more regulated blood sugar level. Fibre can also help make the body’s tissues more sensitive to insulin which helps with regulation. Dogs are best fed in two meals, 12 hours apart, with the insulin injections given after they eat.

For cats, high-protein, low-carbohydrate diets help with regulation. Cats seem to do better fed in multiple small meals throughout the day (if this works with your timetable), so having food available at all times is best for them.

Both Hills and Royal Canin have diets specifically formulated to help regulate diabetes in your pet. 

Hypoglycaemia (low blood glucose) 

Hypoglycaemia usually happens when there is a mismatch between eating and insulin dosing. If the dose is too high, or your pet doesn’t eat you can get hypoglycaemia.

They often look tired, sleepy or weak. If they are roused they can appear drunk and not fully alert. In a worse-case scenario they can seizure. This is obviously an emergency so it is important to know the signs and what to do when this happens.

If they are wobbly or slow, the first thing to do is try to get them to eat. If they won’t eat, sugar-water or honey dribbled onto their tongue may help. If they don’t improve please call the vet for an emergency appointment.

It is very important to know your pet is eating before you give the insulin injection.

Other reasons to call the vet

If you notice your pet going off his/her food, losing weight, having a ravenous appetite, drinking or urinating excessively or becoming disorientated please call us.

Infections can be common in diabetic pets, particularly urinary tract infections. This is due to the bacteria feeding off the sugars in the blood.

It is important to get your pet’s teeth cleaned regularly as the bacteria in dental tartar can seed throughout the body. If you have an intact female, please arrange to get her neutered once her diabetes is stable, as progesterone can interfere with insulin.

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