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Diabetes mellitus ("sugar" diabetes) is
a complex and common endocrine disorder in the cat. It is caused
either by insufficient production of the hormone, insulin, by the
pancreas (type 1 diabetes) or by inadequate response of the
body's cells to insulin (type 2 diabetes). Because diabetic cats
are not able to utilize glucose properly, they ultimately develop
hyperglycemia (high blood sugar levels) and subsequent glucosuria
(sugar in the urine). The glucosuria leads to polyuria (excessive
urination) and polydipsia (excessive thirst). In spite of
maintaining a good appetite, diabetic cats lose weight because
the body's tissues are unable to utilize glucose properly.
Progression of the disease ultimately leads to further metabolic
disturbances and causes vomiting, loss of appetite, weakness, and
dehydration.
Although affecting cats of any breed, sex, or
age, diabetes mellitus most often occurs in older, obese
individuals; males are more commonly afflicted than females. The
exact cause of the disease in cats is not known, although genetic
predisposition, obesity, pancreatic disease, hormonal imbalances,
and certain medications have all been incriminated.
After a period of time, a small percentage of
diabetic cats lose their requirement for specific therapy with
either insulin or hypoglycemic medications.
Signs of
Diabetes Mellitus
Polyuria, polydipsia, increased appetite, and weight loss are
hallmark signs of diabetes mellitus in cats. In the earlier
stages of the disease, cats remain active and alert with few
other signs of disease. However as the disease progresses, poor
skin and haircoat, liver disease, and secondary bacterial
infections become more common. An infrequent disorder called
diabetic neuropathy may cause cats to become progressively weaker
in the rear legs and assume a unique, plantigrade stance. A
dangerous condition called ketoacidosis may develop in some cats.
Signs of ketoacidosis include a loss of appetite, vomiting,
diarrhea, lethargy, weakness, dehydration, and breathing
abnormalities. Without proper and prompt treatment, this
condition ultimately proves fatal.
Diagnosis
Diabetes mellitus is diagnosed based on the cat's clinical signs,
physical examination findings, laboratory test results, and the
persistent presence of abnormally high amounts of sugar in the
blood and urine.
Treatment
Proper treatment of diabetes mellitus is based on the severity of
the disorder. Cats with ketoacidosis require intensive care.
Treatment includes fluid therapy to correct dehydration and
electrolyte abnormalities, and short acting insulin. Diabetic
cats that are not ill usually require insulin injections to be
given once or twice daily under the skin, and a carefully
controlled diet. As an alternative to insulin, treatment with an
oral hypoglycemic drug (see below) may be attempted.
Insulin
Adequate control of most diabetic cats requires long-acting
insulin injections to be given once or twice daily. Each cat
responds differently to insulin, so the proper choice of insulin
type, dose, and frequency of administration needs to be
individually determined. Selection of the appropriate insulin
type, dose, and frequency of administration for an individual
diabetic cat is ideally based on 18- to 24-hour blood glucose
profiles. In order to perform a glucose profile, the cat is
hospitalized, and following insulin administration, frequent
determinations of blood glucose values are made throughout the
day. The proper dose of insulin may change with time and may need
to be adjusted based on blood glucose profiles, intermittent
blood and urine sugar measurements, and response to therapy.
Overdosage of insulin causes hypoglycemia (low
blood sugar). Signs of this potentially dangerous complication
include weakness, listlessness, incoordination, convulsions and
coma. Left untreated, death may result. If hypoglycemia develops,
the cat should immediately be offered its normal food if it is
able to eat. Alternatively, a tablespoon of Karo syrup should be
rubbed on the gums or, if the cat can swallow, given slowly by
syringe into the mouth. Never force fingers, food, or fluids into
the mouth of a convulsing or comatose cat. Your veterinarian
should be contacted immediately if your cat experiences an
episode of hypoglycemia so that further treatment instructions
can be given and a modification of insulin administration, if
necessary, can be made.
Cats requiring excessively high insulin doses
(greater than one to two units of insulin per pound per day)
should be evaluated further. Other diseases may be underlying or
complicating the diabetes mellitus and as a result, necessitate
high insulin dosages. Problems with insulin injection, poor
absorption or too rapid metabolism of insulin, or even insulin
overdose are potential causes of an apparently excessive insulin
requirement.
Oral
Hypoglycemic Medications
Healthy diabetic cats can sometimes be successfully treated with
a hypoglycemic medication, glipizide. Glipizide acts by lowering
blood glucose, but unlike insulin, it is given orally. Adverse
side effects are not common but include vomiting, loss of
appetite, and liver damage. If hyperglycemia persists after one
or two months of therapy, or if the cat becomes ill or
ketoacidotic, glipizide therapy should be discontinued and
insulin therapy instituted.
Diet
Obese diabetic cats should lose weight gradually, with no more
than 3 percent of their body weight lost per week. Your
veterinarian will help in tailoring a safe weight-loss program
for your cat. High fiber, high complex carbohydrate diets are
useful, not only by assisting in weight loss, but by helping to
control blood glucose levels after eating. Underweight diabetic
cats should be fed a high fiber diet only after reaching their
ideal body weight after being fed a high calorie diet.
Cats receiving insulin once daily should be fed
half the daily food requirement at the time of the injection and
the remaining half at the time of peak insulin activity (as
determined by a blood glucose profile). If receiving twice daily
insulin injections, cats should be fed half the daily ration at
each administration. Cats receiving oral hypoglycemic medication
should be fed a high fiber diet, but ideally as multiple small
meals consumed throughout the day.
Home Care
Topics to be thoroughly discussed with your veterinarian include:
- Insulin storage and handling
- Insulin administration
- Signs and treatment of hypoglycemia
- Diet
- Monitoring at home
Prognosis
Managing a diabetic cat requires good communication between you
and your veterinarian. A diabetic cat may live many healthy years
with owners who are willing to put forth the effort of monitoring
the cat's condition daily. Cats tend to be difficult to maintain
on the same regimen for long periods of time, and increases or
decreases may need to be made in drug dosages.
Prepared by the Cornell Feline Health
Center, Cornell University, College of Veterinary Medicine,
Ithaca, New York 14853-6401. The ultimate purpose of the Feline
Health Center is to improve the health of cats by developing
methods to prevent or cure feline diseases and by providing
continuing education to veterinarians and cat owners. Much of
that work is made possible by the financial support of friends.
©1996 by Cornell University. All rights reserved. Cornell
University is an equal opportunity, affirmative action educator
and employer. |
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