Diabetes is a common hormonal disorder in pets and is manifested as a disorder of carbohydrate, fat and protein metabolism in the body. Diabetes occurs when there is lack of insulin or it is present in insufficient quantities.
Insulin is produced in the pancreas and it facilitates entry of glucose into the cells. If insulin is not present the cells are starved for glucose and start using fat and proteins as a source of energy leading to the production of ketone bodies. Ketone bodies are very toxic to the body and cause decrease of blood pH making it more acidic. Ketone bodies can be found in starving animals as well but they disappear once the animal starts eating normally.
Due to the lack of insulin, there is high quantity of glucose in the blood which eventually spills over into urine and this is when the symptoms of diabetes mellitus become obvious.
The two most common types of diabetes mellitus are type 1 and 2. Type 1 is characterised by the destruction of insulin secreting cells in the pancreas by an immune mediated process. It usually occurs in dogs and this type always needs insulin injections to keep it under control.
Type 2 occurs in cats and in this type of diabetes some insulin secreting ability is still present in the pancreas. Some of the cats with type 2 diabetes may not need insulin. However the great majority of cats lose the ability to produce insulin and end up with type 1 diabetes.
Keeshond, Cairn Terrier and Miniature Pincher get diabetes more often than other dog breeds. Middle aged female dogs are prime candidates for diabetes. In cats there is no breed predilection and it usually affects middle age to older male cats.
Medications (cortisone, progesterone analogues), genetic factors, history of pancreatitis, obesity and some concurrent diseases such as Cushing’s disease can make pets more likely to develop this disease. Entire (not desexed) bitches can develop diabetes as a result of progesterone activity.
How is diabetes mellitus diagnosed?
A simple blood test is usually all needed. Urine tests such as a dipstick test can also be useful to diagnose diabetes mellitus (presence of glucose in the urine) and confirm ketoacidosis if any (presence of ketone bodies in the urine). Cats can have high blood glucose as a result of stress and in some cases they may need fructosamine levels checked.
How do I know that my pet has diabetes?
The symptoms in dogs and cats are excessive drinking, urination and appetite with weight loss. In advanced stages of diabetes your pet may become lethargic, sluggish and depressed which usually occurs in the case of ketoacidosis. Appetite is reduced and vomiting can occur. Dogs tend to develop cataracts and cats can also in rare cases. In cats plantigrade posture of hind limbs can occur in which the cat is walking on hocks instead of paws. This is the results of neuropathy due to diabetes and is a reversible condition. Both dogs and cats can have enlarged livers and some cats develop jaundice as a result of it.
Can my pet be treated for diabetes?
The treatment of diabetes in dogs and cats is often successful and most animals with the disease will have a normal life expectancy. The treatment depends on the severity of the diabetes. Uncomplicated cases of diabetes are usually treated as outpatients.
Treatment of diabetes can be complex and it can require a high level of the owner’s commitment. The issues that have to be addressed in the treatment of diabetes mellitus are:
Nutrition is very important in diabetic animals. A proper diet can reduce the dose of insulin and improve glycaemic control. Dogs, unless emaciated, need a high fibre diet that is high in complex carbohydrates and low in fat. A high fibre diet will keep calories constant and helps with obesity management. Cats need a high protein and low carbohydrate diet.
Both dogs and cats achieve better control on dry food rather than wet. However in some cases the pet may refuse to eat prescription diets and as a result of starvation diabetes can get out of control. If this is the case there are other approaches available and your vet can advise you on those. Most pets are fed twice daily and insulin injections are given around the same time.
Exercise should be kept constant and moderate. Strenuous exercise lowers blood glucose and as a result your pet could become hypoglycaemic (low blood glucose).
Medications are the cornerstone of the treatment. There are many different types of insulin but Caninsulin and Glargine are two most commonly used. Caninsulin is predominantly used in dogs and occasionally in cats. Cats tend to respond well to human insulin called Glargine which in some cases can cure diabetes mellitus for good. Depending on the result of the blood glucose curve your vet will calculate the dose of insulin and frequency of administration. Most dogs and cats need insulin twice daily.
Insulin is a very fragile medication and many things can affect its effectiveness. Rough handling and vigorous shaking of a bottle should be avoided. It must not be frozen or left outside of the fridge because it becomes inactive. It is crucial to mix it thoroughly prior to measuring the dose especially if the bottle is brand new. Caninsulin precipitates at the bottom of the bottle which is not an issue with Glargine. Insulin works best when administered in an area of the body without too much fat under the skin since fat interferes with the absorption of insulin. Flanks are good places to inject. Most vets will give you a crash course on all the basics and teach you how to administer the injection properly. Once the insulin dosage is right, it is crucial to give the same dose. Make sure if you have any questions to give our vets a call and get proper advice.
Do not use different brands of syringes to inject your dog or cat since there are many different on the market and all are calibrated differently. Some contain 40 international units per millilitre (Caninsulin) and some 100 (syringes for human insulin). If you swap 40 IU syringe for 100IU and use the same dose you will give your pet about half the dose required which can jeopardise its health.
In cats with type 2 diabetes (non insulin dependent) other medications may be used to stimulate the production of insulin from the pancreas together with high protein, low carbohydrate diets.
Many pets suffering from diabetes are more likely to have chronic urinary bladder infections and dental health issues. In order to keep blood glucose stable while on insulin all infections must be kept under control.
Monitoring of diabetic pets is crucial. If not done properly the final outcome is unlikely to be satisfactory. A blood glucose curve is the golden standard in monitoring diabetic patients. Multiple measurements of blood glucose are taken at two hourly intervals and plotted on a chart. Depending on the results an adjustment in insulin dosage is made.
Initially we do not aim to get the dose perfect too quickly because the body needs time to get used to the insulin. A blood glucose curve is done whenever the dose of insulin is changed. Most pets are stabilised within three months and then they need a six monthly blood glucose curve. These are done to make sure the insulin requirements have not changed.
Some pets need fructosamine levels checked, cats in particular. Fructosamine occurs when glucose binds to blood proteins. Contrary to blood glucose level, fructosamine is unaffected by concurrent disease and stress. It tells us the current level of glycaemic control. If diabetes is well managed the levels are lower. Fructosamine tests needs a single blood sample and no hospitalisation is needed.
What are the complications of the treatment?
Hypoglycaemia, cataracts in dogs and ketoacidosis can be encountered in diabetic patients. Hypoglycaemia or low blood sugar occurs as a result of insulin overdose. The symptoms are shaking, twitching of ears and face, weakness and seizures. Hypoglycaemia needs urgent treatment because if not treated it can be lethal. Honey or sugar dissolved in water and put into the mouth resolves the problem quickly. Once your pet is stable for transport it must be seen by a vet to work out how to adjust the insulin dose. Unfortunately cataracts are unavoidable even if the control is perfect. Cataract is an increase in opacity of the lens. Mature cataracts can be extracted at specialist centres and artificial lenses placed inside the eye so the vision is not affected.
What is ketoacidosis?
Ketoacidosis is the worst form of diabetes mellitus, a true medical emergency. It occurs when dog or cat has high blood glucose levels for a while or the insulin dose is too low. Pets with ketoacidosis have a severe electrolyte imbalance (low potassium), hyperglycaemia (high blood glucose), ketosis (presence of ketone bodies in the blood) and acidosis (low Ph of blood). Ketoacidotic patients have a guarded prognosis and need hospitalisation for 3-5 days at least. Intensive treatment which consists of insulin, intravenous fluids and correction of electrolyte imbalances is needed to give your pet the best chance of survival. Once stabilised your pet is treated as a case of uncomplicated diabetes (see above).