1500 East Boston Post Road o Mamaroneck, NY 10543

Judith S. Johnessee, MS, DVM
Diplomate, American College of
Veterinary International Medicine


Diabetes mellitus is caused by a deficiency of the hormone insulin. Insulin is normally produced by the pancreas, a small gland located between the stomach and part of the small intestine. Insulin is necessary to transport glucose from the blood stream into the cells of the body. Without insulin, the glucose produced by the metabolic machinery of the body cannot get into the cells. The net result is that the cells starve while excess glucose builds up in the blood and finally spills over into the urine.

Because the cells are starving, the body mobilizes more and more of the energy stores causing the animal to lose weight and muscle mass. The useless glucose in the blood stream is removed by the liver and stored-as fat in many body organs. The combination of fatty buildup and cellular starvation causes a complex series of metabolic derangement’s, resulting in excessive water consumption and elimination, elevated liver and kidney tests, mental depression and decreased resistance to infection. Eventually the body can no longer compensate for these problems and the extreme reliance of the cells on the breakdown of stored fat for energy leads to ketoacidosis. This is signaled by the appearance of ketones as well as sugar in the urine and the development of severe acid-base imbalances, vomiting,

dehydration and extreme depression. This state is rapidly fatal unless treated.

The cause of diabetes in most animals is unknown although severe pancreatitis can be a causative factor, as can Cushing’s disease, an abnormality of the adrenal glands. Administration of cortisone compounds for a long time (months to years) or progesterone (Ovaban) can also precipitate the disease. Occasionally an animal will become diabetic for a short period of time and then become normal again. Most of these animals, however, ultimately become permanently diabetic.

Dogs and cats cannot be controlled completely by diet, exercise and oral agents like people can. They require daily injections of insulin, either once or twice a day, depending upon the animal's requirements and the type of insulin. Insulin comes in several forms: regular, NPH and protamine zince (PZI). These types have different duration’s of action. In people regular insulin lasts 6 hours, NPH insulin lasts approximately 24 hours and PZI about 36 hours. In dogs and cats the duration is very variable from animal to animal and needs to be determined for each individual case. In general dogs will require once to twice daily injections of NPH insulin and cats may require anywhere from once daily NPH or PZI to twice daily NPH.


Specifically, what your animal needs will be determined by following blood glucose’s every few hours for a 24 hour period. We have found that the duration of action of a specific insulin may change over time. Whenever your pet's insulin regulation becomes difficult, we will probably want to follow the blood glucose levels over 24 hours.

The amount of insulin your animal requires is determined by three things: diet, exercise and concurrent diseases. Regulation becomes much easier if diet and exercise are kept constant. This means twice daily feeding of constant amounts at a relatively constant time (approximately 12 hour intervals). Record your pet's weight once a week to watch for weight loss or gain.

The amount of insulin given is determined each morning by checking the amount of glucose in the urine. Depending upon the amount of glucose present, you will adjust the insulin dosage up or down according to a chart prepared specifically for your animal. In general the insulin dosage may rise to as much as I unit per pound in a normal animal. The dosage often fluctuates up and down, but sudden large changes in the dosage should be reported. You should keep a record (the kitchen calendar is probably handiest) of the urine glucose and ketones and the insulin dosage given. Bring this with you whenever your pet is rechecked. If your pet appears weak, wobbly, dazed or drunk 6 to 14 hours after insulin administration give some Karo syrup orally then force feed a small meal; and then call the veterinarian. If your animal is unconscious take it immediately to the nearest veterinarian. Do not try to put Karo syrup down the throat of an unconscious animal. Insulin shock and sugar shock cannot be differentiated without laboratory testing. Too much sugar will not kill an animal suddenly; too much insulin will. Never assume the animal needs more insulin, always assume he needs-more glucose. Similarly, if your animal moves while you are giving the insulin, do not try to estimate the amount lost, or you may estimate wrong and give an overdose. Just skip that day's dose and give it the next day.

Back to animal care page