By Alan Schreiner, DVM, DACVIM
As many of you already know, our four-legged friends are susceptible to some of the same diseases that affect us. One of those diseases is diabetes mellitus or high blood sugar. In animals as in people, diabetes mellitus occurs when the body is not producing enough insulin or because the cells in the body cannot respond to the insulin produced. Insulin is a protein made by the pancreas that helps keep the sugar in the blood within a narrow range. Like people, animals with diabetes mellitus are classified into two categories: Type 1 diabetics are insulin-dependent and require injections of insulin while Type 2 diabetics are characterized by having insulin resistance and can be insulin-dependent or non-insulin dependent. Both Type 1 and Type 2 diabetics are recognized in dogs and cats.
Occurrences in Cats vs. Dogs
Non-insulin dependent diabetes mellitus (NIDDM) is more frequently recognized in cats than in dogs and accounts for as many as 30-50% of diabetic cats. One big difference between cats and people is the phenomenon of transient diabetes mellitus. Transient diabetes can be seen in approximately 20% of our diabetic cats. These cats will appear to have insulin-dependent diabetes mellitus (IDDM) initially, then revert to a normal state, not requiring any insulin therapy and have normal blood sugar levels. These patients can then swing back to IDDM. This phenomenon can occur multiple times during the cat’s life as a diabetic.
People always want to know if their pet is at risk for developing diabetes mellitus. No one can predict which pets will develop diabetes, but in general we see occurrences in dogs that are four to 14 years-old with a peak between seven to nine years-of-age. In dogs, females are about twice as likely to develop diabetes as males are. Any breed can develop diabetes mellitus, but the breeds that are commonly seen are Miniature Poodles, Cairn Terriers, Dachshunds, Miniature Schnauzers and Beagles.
As for cats, they are typically older than six years-of-age, but diabetes mellitus can show up at any age. The neutered male cat is predominantly seen verses the spayed female cat and there are no apparent breed predispositions reported.
Signs and Symptoms: Diagnosing the Diabetic Pet
The signs and symptoms seen by most pet owners are very similar to what people experience; an increase in water consumption and urination frequency and an increase in appetite but accompanied by weight loss. One way to think of diabetes mellitus is starvation in the face of plenty.
When a dog or cat is presented to their veterinarian for any of these signs or combination of symptoms, the doctor will order some diagnostic tests. These tests usually include a complete blood count (CBC), a chemistry panel, in cats a thyroid level, and a urinalysis (UA). The classic results will show elevation of sugar (otherwise known as glucose) in both the blood and the urine. Other abnormalities may also be present, such as signs of infection on the CBC, elevation of liver enzymes is common, and ketones maybe noted in the urine. A urine culture should always be done because of the high incidence of concurrent urinary tract infections. Additional diagnostic test may be ordered based on physical exam findings, results of the blood work, or previous medical problems.
Treatment and Next Steps
In most animal patients, successful treatment is centered around an ongoing schedule of insulin injections. Persistence of signs and the development of chronic complications are directly correlated with the severity and duration of the high blood sugar levels. The goals of therapy are to limit blood sugar fluctuations and maintain nearly normal sugar levels to help minimize signs and symptoms. This can be accomplished through proper insulin administration, diet and exercise. In addition, avoiding or controlling current inflammation, infections, and hormonal changes (intact males and females) is important for maintaining good blood sugar control. Although, we attempt to keep the blood sugar from rising too high, we must also guard against the development of low blood sugar which can be a serious and potentially fatal complication of therapy.
As in people, our four-legged patients can develop, over time, complications associated with diabetes mellitus. In dogs, cataracts are a common complication and cats can develop nerve problems in their legs just like people. Bacterial infections, especially in the urinary tract, are also common and urine cultures are done periodically to monitor for their development.
It is recommended that the treatment be monitored regularly by the veterinarian with blood glucose curves, fructosamine levels, and sometimes glycosylated hemoglobin levels checked. The blood glucose curve is done to monitor the effect of the insulin on the blood sugar levels. The curve is usually done in the veterinarian’s office during the course of a day. Blood samples are taken every few hours throughout the day and the readings are used to create a graph. This graph helps the veterinarian decide if the insulin is adequately controlling the blood sugar level. If not, then changes are made to the insulin dose or type. If a change is made, then the patient’s body will take about seven to 10 days to adjust to the new regime. Another blood glucose curve will be scheduled to recheck the effects of the change.
The other two tests, fructosamine and glycosylated hemoglobin, are used to obtain an average blood glucose level over different periods of time. These tests are helpful in detecting deteriorating blood glucose control, thus allowing intervention before a problem develops.
Identified early, Diabetes Mellitus in dogs and cats can be successfully managed through the right nutrition, exercise, and, if necessary, regular insulin injections. While there is no cure for the disease, proper managed care can help the pet live a happy, active life. Your veterinarian is an essential partner to this care and can give advice on the best preventative and management programs.
To learn more about the diabetic pet, please visit www.petdiabetesmonth.com.