Diabetes mellitus | Newsletters

Diabetes mellitus occurs when the pancreas doesn't produce enough insulin. Insulin is required for the body to efficiently use sugars, fats and proteins.

Predisposition

Diabetes most commonly occurs in middle age to older dogs and cats, but occasionally occurs in young animals. When diabetes occurs in young animals, it is often genetic and may occur in related animals. Diabetes mellitus occurs more commonly in female dogs and in male cats.

Certain conditions predispose a dog or cat to developing diabetes. Animals that are overweight/obese or those with inflammation of the pancreas are predisposed to developing diabetes. Certain drugs have been shown to interfere with insulin, leading to diabetes. Glucocorticoids, which are cortisone-type drugs, and hormones used for heat control are drugs that are most likely to cause diabetes. These are commonly used drugs and only a small percentage of animals receiving these drugs develop diabetes after long-term use.

Symptoms

The body needs insulin to use sugar, fat and protein from the diet for energy. Without insulin, sugar accumulates in the blood and spills into the urine. Sugar in the urine causes the pet to pass large amounts of urine (water) and to drink lots of water in order to compensate for what is been lost. Levels of sugar in the brain control appetite. Without insulin, the brain becomes sugar deprived and the animal is constantly hungry, yet they may lose weight due to improper use of nutrients from the diet. Untreated diabetic pets are more likely to develop infections and commonly get bladder, kidney, or skin infections. Diabetic dogs, and rarely cats, can develop cataracts in the eyes. Cataracts are caused by the accumulation of water in the lens and can lead to blindness. Fat accumulates in the liver of animals with diabetes. Less common signs of diabetes are weakness or abnormal gait due to nerve or muscle dysfunction. There are two major forms of diabetes in the dog and cat: (1) uncomplicated diabetes, and (2) diabetes with ketoacidosis (complicated and potentially life-threatening). Pets with uncomplicated diabetes may have the signs just described but are not extremely ill. Diabetic pets with ketoacidosis are very ill and may be vomiting and depressed.

Diagnosis

The diagnosis of diabetes is made by finding a consistently large increase in blood sugar and a large amount of sugar in the urine. Animals, especially cats, stressed by having a blood sample drawn, can have a temporary increase in blood sugar, but there is no sugar in the urine. A blood screen of other organs is obtained to look for changes in the liver, kidney and pancreas. A urine sample may be cultured to look for infection of the kidneys or bladder. Diabetic patients with ketoacidosis may have an elevation of waste products that are normally removed by the kidneys.

Treatment

The treatment is different for patients with uncomplicated diabetes and those with ketoacidosis. Ketoacidotic diabetics are treated with intravenous fluids and rapid-acting insulin. This treatment is continued until the pet is no longer vomiting and is eating, then the treatment is the same as for uncomplicated diabetes.

Diabetes is managed long-term by the injection of insulin by the owner once or twice a day. Some diabetic cats can be treated with oral medications instead of insulin injections, but the oral medications are rarely effective in the dog. There are three general types of insulin used in dogs and cats:

• Short-acting insulin (regular or crystalline) is used in sick diabetic animals until they are eating again – very useful in diabetic emergencies
• Intermediate-acting insulins (currently, only one veterinary insulin is registered in South Africa and it belongs to this class of insulins) – not used for diabetic emergencies.
• Long-acting insulins - not used for diabetic emergencies.

Insulin comes from different sources including beef or pork pancreas and a human genetically engineered form called Humulin. The availability of animal-source insulins continues to decline.

In general, cats and small dogs need insulin injections more frequently, usually twice daily, compared to large breed dogs that may only require one dose of insulin daily. The action of insulin varies in each individual and some large dogs will need 2 insulin shots daily. The insulin needs of the individual animal are determined by collecting small amounts of blood for glucose (sugar) levels every 1-2 hours for 12-24 hours. This is called an insulin-glucoseresponse curve. When insulin treatment is first begun, it is often necessary to perform several insulin-glucoseresponse curves to determine:

• which insulin type to use
• how much insulin to give
• how often to give insulin
• when is the best time to feed the animal

The animal's insulin needs may change over time requiring a change in insulin type or frequency of injection. Insulinglucose- response curves are usually performed several days after a change in insulin is made.

Before you give insulin injections to your pet, your veterinarian will show you how to:

• handle insulin
• use a syringe
• draw insulin from the bottle in the correct amount
• give your pet the insulin shot

Insulin is fragile and will become less effective or even inactive, if it gets too hot or cold, or is shaken vigorously. Pay attention to the expiration date on the bottle. Discard insulin that is outdated.

Lifestyle

Insulin injections are not as perfect as the insulin produced by the pancreas. Blood sugar levels will not always be normal in diabetic pets. The goal of treatment is to reduce the signs of diabetes. When diabetes is well controlled with insulin, the pet should drink, eat and urinate normal amounts. They should have a good appetite, without becoming fat and should have normal activity.

Insulin needs are closely related to the type of food eaten by the pet. Your veterinarian will recommend a specific diet and feeding regimen that will enhance the effectiveness of insulin. If your pet is overweight, s(he) will be placed on a weight-reducing diet. As the pet loses weight, less insulin will be needed. Only feed the recommended diet. NO table scraps or treats that are not part of the recommended diet.

Heavy exercise will reduce the amount of insulin needed. It is important to talk to your veterinarian before making changes in diet or exercise.

There is always some risk that a diabetic patient will develop low blood sugar. Signs of low blood sugar include weakness, staggering, seizures, or just being more quiet than usual. You should keep corn syrup on hand to rub on the animals gums if they have signs suggestive of low blood sugar. Don't pour large amounts of corn syrup in the mouth of an animal that is not fully conscious as the syrup may be inhaled into the lungs.

Because insulin needs vary with the activity and lifestyle of your pet, you may want to keep a written daily log of:

• the dose of insulin
• location in which the insulin is injected
• any changes in the pet’s activity or appetite

Your veterinarian may ask you to check your pet's urine for sugar using a test strip. If your pet is well regulated on insulin, the sugar readings in most urine samples will be negative or trace. The strips may have color pads only for glucose or for glucose and ketones.

The strip is placed in fresh urine and the color change compared with the colors on the bottle. Be sure to follow the label instructions for timing when to read the results.

You should never change the dose of insulin based on the urine sugar reading alone. Animals can have lots of sugar in their urine either when the insulin dose is too low or is too high. If your pet is difficult to regulate with the proper dose of insulin you may be taught how to take a small blood sample from your pet to measure blood sugar readings at home. There are many styles of machines used to measure blood sugar. The machines are called glucometers. They use color sticks which are read by the glucometer rather than by color changes you can see. Different styles of glucometers use different color strips.

Diabetes is rarely reversible in dogs, but diabetic cats will sometimes regain the ability to produce their own insulin in the pancreas. Cats that developed diabetes after receiving long term glucocorticoids or hormones are more likely to stop needing insulin after a while compared to cats that developed diabetes without a known cause.

You should have your diabetic pet evaluated by a veterinarian at 2-4 month intervals or anytime another health problem develops. The development of other health problems will often interfere with insulin regulation.