Hypoglycemia (Low Blood Sugar) in Cats

Overview of Hypoglycemia in Cats

Hypoglycemia is defined as a blood glucose (sugar) concentration of less than 70 milligrams per deciliter(mg/dl) of blood. Symptoms depend on how quickly the blood glucose concentration decreases, but rarely occur until it falls below 50 mg/dl.

Below is an overview of Hypoglycemia in Cats followed by detailed information about the causes, diagnosis and treatment of this condition.

Symptoms reflect the rate of decrease of the blood glucose concentration, the underlying cause of hypoglycemia, and the chronicity of the problem. One common form of hypoglycemia is called juvenile hypoglycemia because it occurs in kittens less than 3 months of age. Juvenile hypoglycemia is common in kittens because they have not fully developed the ability to regulate their blood glucose concentration and have a high requirement for glucose. Stress, cold, malnutrition, and intestinal parasites are problems that may precipitate a bout of juvenile hypoglycemia.

Other Causes of Hypoglycemia in Cats

• Fasting before vigorous exercise
• Excessive insulin administration (may occur in cats with diabetes)
• Insulin-producing tumors of the pancreas
• Severe liver disease
• Other tumors that produce insulin-like factors
• Portosystemic shunts
• Hereditary diseases arising from abnormal storage of glucose
• Serious systemic bacterial infection

What to Watch For

• Loss of appetite
• Extreme lethargy
• Incoordination
• Trembling and muscular twitching
• Weakness
• Seizures
• Unusual behavior
• Dilated pupils and apparent blindness
• Stupor or coma

Diagnosis of Hypoglycemia in Cats

Diagnostic tests are needed to identify hypoglycemia and determine its cause. Your veterinarian may recommend the following diagnostic tests:

• A complete medical history and thorough physical examination
• Measurement of blood glucose concentration
• Other diagnostic tests such as complete blood count (hemogram or CBC), routine serum biochemistry tests, urinalysis, and serum insulin concentration to establish the underlying cause of hypoglycemia
• Ultrasound examination of the abdomen to identify a pancreatic or other tumor that could be causing hypoglycemia

Treatment of Hypoglycemia in Cats

Ultimately, treatment for the underlying cause of hypoglycemia is necessary, but initially, your veterinarian may administer glucose orally or by intravenous injection to increase blood glucose concentration.

Home Care and Prevention

At home it will be necessary to observe your cat’s general activity level, appetite and attitude. If you have reason to suspect hypoglycemia, you should rub Karo® syrup or other high sugar concentration syrup on your cat’s gums and call your veterinarian immediately.

Some preventative measures can help. Provide a warm environment, frequent feedings, routine vaccinations and de-worming procedures for kittens as recommended by your veterinarian. Also, provide frequent, regular feedings. Young kittens should be allowed to eat as much as they want. Be sure to feed a high quality pet food.

In-depth Information on Hypoglycemia in Cats

Common causes of hypoglycemia include the following disorders:

• Insulin-producing tumors of the pancreas, such as beta cell tumor or insulinoma
• Glycogen storage disease, which is a hereditary disorders in which enzyme deficiencies cause abnormal storage of glucose in the liver as starch
• Hypopituitarism, a decreased secretion of regulatory hormones from the pituitary gland
• Insulin overdosage as may occur in pets with diabetes mellitus
• Juvenile hypoglycemia, which is hypoglycemia in puppies associated with stress, cold, infrequent feeding, and intestinal parasites
• Laboratory error. Blood glucose concentration can decrease by as much as 10 milligrams per deciliter of blood for every hour the blood is allowed to stand before being processed by the laboratory. Improper sample handling is a common cause of apparent hypoglycemia in blood samples shipped long distances to laboratories. To avoid this error, your veterinarian can use a machine called a centrifuge to spin the blood cells down and separate serum from the blood before shipping the sample to the laboratory for analysis.
• Liver disease
• Malabsorption, or impaired intestinal absorption of nutrients
• Malnutrition. In actuality, prolonged fasting or loss of appetite in otherwise normal adult dogs is not a common cause of hypoglycemia.
• Tumors of organs other than the pancreas that produce insulin-like substances that can cause hypoglycemia
• Orally-administered hypoglycemic drugs such as the sulfonylureas, more commonly used to treat diabetes mellitus in some human patients
• Portosystemic shunt, which is an abnormal blood vessel present at birth that causes blood from the intestines to by-pass the liver
• Advanced pregnancy rarely can be associated with hypoglycemia
• Glucose in the urine due to abnormal function of the kidney tubules rarely can be associated with low blood sugar concentration
• Severe systemic bacterial infection (sepsis)

In-depth Information on the Feline Hypoglycemia

Other medical problems can lead to symptoms similar to those encountered in cats with hypoglycemia. It is important to rule out these conditions before establishing a definite diagnosis:

• Hepatoencephalopathy. This is abnormal brain function caused by severe liver disease or shunting of blood around the liver
• Hypocalcemia. This is blood calcium concentration that is lower than normal
• Central nervous system disorders
• Spinal cord disorders causing hind limb weakness
• Syncope or fainting

Diagnosis In-depth

Diagnostic tests must be performed to confirm the diagnosis of hypoglycemia and exclude other diseases that may cause similar symptoms. Your veterinarian will probably recommend the following:

• A complete medical history and physical examination. Your veterinarian will ask specific questions about you cat’s appetite and eating habits.
• Blood glucose concentration. Your pet’s blood sugar will be measured, and if the reading is normal, it may be followed by a fasting blood sugar and repeated measurements during fasting.

Your veterinarian may also recommend additional diagnostic tests to exclude other conditions or to better understand the impact of hypoglycemia on your cat. These tests ensure optimal medical care and are selected on a case-by-case basis. Examples include:

• A complete blood count (CBC or hemogram) to identify anemia and evaluate for other problems such as infection or inflammation.
• Serum biochemistry tests to identify underlying disease processes that may contribute to the development of hypoglycemia or to identify complicating disease processes.
• Urinalysis to evaluate kidney function, identify glucose in the urine, and detect the presence of white blood cells in the urine, which would indicate urinary tract infection.
• Fecal flotation to identify the presence of parasites that can cause hypoglycemia.
• Blood concentration of bile acids to evaluate liver function since some animals with liver failure develop hypoglycemia.
• Serum insulin concentration may be determined in conjunction with blood glucose concentration to identify an insulin-secreting tumor of the pancreas (insulinoma or beta cell tumor).
• X-rays of the abdomen and chest may be performed to look for tumors that may be associated with hypoglycemia. X-rays of the chest often are performed to check for tumors that may have spread (metastasized) to the lungs. A small liver on abdominal X-rays may indicate chronic scarring (cirrhosis) or shunting of blood around the liver caused by an abnormal blood vessel (portosystemic shunt). A hazy appearance to the abdominal X-ray can be caused by peritonitis.
• An abdominal ultrasound may be performed to evaluate your cat for the presence of tumors that could cause hypoglycemia. Insulin-producing tumors of the pancreas (insulinoma or beta cell tumor) often are very small and may not be evident on ultrasound examination. Fortunately, these tumors are very rare in cats.
• Hypoglycemia that remains unexplained after complete diagnostic evaluation may necessitate referral to a specialist in veterinary internal medicine.

Treatment In-depth

Optimal therapy of any serious or persistent medical condition depends on establishing the correct diagnosis. There are several potential causes of hypoglycemia and the underlying cause of hypoglycemia must be determined before definitive treatment can be recommended.

Initial therapy should be aimed at diagnosis and treatment of the underlying causes of hypoglycemia. Your veterinarian may recommend or perform the following treatment measures:

• Supplemental dextrose by administration of corn syrup (Karo® syrup) on the cat’s gums or a 50 percent solution of glucose administered orally. Special care should be taken to be certain the cat has a normal swallowing reflex so as to prevent aspiration of the glucose solution into the lungs. In some cats, it may be necessary to administer a sterile solution of dextrose by intravenous injection.
• An intravenous catheter and administration of an electrolyte solution that also contains dextrose may be necessary.
• Warming of patients with low body temperature and close monitoring of body temperature is important, especially in kittens.

Your veterinarian will attempt to identify the underlying cause of hypoglycemia and treat it appropriately, such as removing the tumor associated with hypoglycemia, providing frequent small meals, and treating body wide infections. Treatment measures after emergency care may include:

• The cat may be hospitalized for observation and treatment of hypoglycemia. Blood glucose concentrations may be checked frequently until the patient has been stabilized.
• Your cat will be fed small meals frequently if possible. The diet should be high in protein, fat and complex carbohydrates. A combination of canned and dry foods fed 3 to 6 times per day is recommended.
• Glucocorticoids may be recommended for cats with hypoglycemia caused by a tumor.
• A drug called diazoxide (Proglycem®) also may be considered for cats with tumor-induced hypoglycemia.

Prognosis for Feline Hypoglycemia

Appropriate diagnosis and treatment of the underlying disorder will assure the best possible prognosis, which is dependent on the cause of hypoglycemia. In cases of juvenile hypoglycemia and insulin overdose hypoglycemia, prognosis is generally good.

The prognosis for cats with hypoglycemia associated with body wide infection (sepsis) is dependent on the underlying cause of the systemic infection and how effectively it can be treated.

Follow-up Care

Optimal treatment for your cat requires a combination of home and professional veterinary care. Follow-up can be crucial and may include the following recommendations:

• Administer any medications prescribed by your veterinarian. Inability to medicate properly can be a reason for treatment failure.
• Feed your cat frequent small meals and observe your cat’s general activity level and appetite. Monitor him for signs of recurrent hypoglycemia (lethargy, weakness, staggering, unusual behavior, apparent blindness, muscular twitching, seizures).
• Have your veterinarian check your cat regularly for blood glucose determinations.