hypoglycemia

Hypoglycemia in Dogs

Hypoglycaemia is caused by low blood glucose in an exercising dog. Most cases occur as sudden collapse or exhaustion during hard exercise in previously healthy dogs. A dog may have repeated collapses, though there is evidence that as the dog gets older the chances of an episode reduces.

Hypoglycaemia can cause wobbliness, collapse, fits and even death. Offer small meals or treats during the course of a day to prevent it. Because the signs are vague, several conditions that cause collapse in exercising dogs might also be considered. If a dog collapses for no obvious reason, give it sugar, honey or glucose - you may save its life and are very unlikely to cause harm. Many people offer chocolate bars, and, though I normally avoid giving chocolate, in this instance we balance the slight risk of side effects with the possibility of saving a life.
Harvey Caruthers

Hypoglycemia in Dogs

Dr. Debra Primovic

Hypoglycemia is defined as a blood glucose or blood 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.

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 puppies less than three months of age. Juvenile hypoglycemia is common in puppies 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. Toy breed dogs less than three months of age are most commonly affected.

Other causes of hypoglycemia include fasting before vigorous exercise which may be a factor in the syndrome called "hunting dog hypoglycemia"; Addison's disease, an endocrine problem caused by a lack of hormone production by the adrenal glands which can cause weakness, vomiting, diarrhea, and collapse; excessive insulin administration, as may occur in pets with diabetes mellitus; insulin-producing tumors of the pancreas, called "insulinomas" or "beta cell tumors"; severe liver disease; some other tumors that produce insulin-like factors; dogs with portosystemic shunts, which are congenital blood vessel abnormalities the cause blood from the intestines to by-pass the liver; hereditary diseases arising from abnormal storage of glucose as starch in the liver, or glycogen storage disease; and serious systemic bacterial infection, or sepsis.

What to Watch For

Loss of appetite
Extreme lethargy
Incoordination
Trembling
Muscular twitching
Weakness
Seizures
Unusual behavior
Dilated pupils
Apparent blindness
Stupor or coma

Diagnosis
Diagnostic tests are needed to identify hypoglycemia and determine its cause.

Tests may include:

A complete medical history and physical examination

Measurement of blood glucose concentration

Other diagnostic blood tests such as complete blood count (also called hemogram or CBC), routine serum biochemistry tests, urinalysis, and serum insulin concentration to try and establish the underlying cause of hypoglycemia.

Ultrasound examination of the abdomen to try and identify a pancreatic or other tumor that could be causing hypoglycemia.

Treatment
Treatments for hypoglycemia may include the following:

Administration of glucose orally or by intravenous injection to increase blood glucose concentration.

Treatment for the underlying cause of hypoglycemia

Home Care and Prevention
Administer as directed any medications prescribed by your veterinarian. Observe your dog's general activity level, appetite and attitude.

If you have reason to suspect hypoglycemia, you should rub Karo® syrup on your dog's gums and call your veterinarian immediately. Schedule an appointment with your veterinarian to identify, treat, and monitor the underlying cause of hypoglycemia.

See your veterinarian for regular check-ups as directly.

Provide a warm environment, frequent feedings, routine vaccinations and de-worming procedures for puppies as recommended by your veterinarian. Provide frequent, regular feedings. Young puppies should be fed at least 3 to 4 times a day.

Feed a high quality dog food and provide extra feedings or snacks to working dogs.

Section: Information In-depth
Other medical problems can lead to symptoms similar to those encountered in dogs with hypoglycemia. It is important to exclude these conditions before establishing a definite diagnosis:

Hepatoencephalopathy, which is abnormal brain function caused by severe liver disease or shunting of blood around the liver

Hypocalcemia, or lower than normal blood calcium concentration

Central nervous system disorders

Spinal cord disorders causing hind limb weakness

Syncope (fainting)

Common causes of hypoglycemia include the following disorders:

Addison's disease, which is an endocrine disorder caused by insufficient hormone production by the adrenal glands

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)

Veterinary Care In-depth

Veterinary care should include diagnostic tests and subsequent treatment recommendations.

Diagnosis In-depth

Diagnostic tests must be performed to confirm the diagnosis of hypoglycemia and exclude other diseases that may cause similar symptoms. Tests may include:

A complete medical history and physical examination with specific questions about your dog's appetite and eating habits

Repeated fasting blood glucose concentration measurements to identify hypoglycemia if the initial blood glucose concentration is normal

Your veterinarian may recommend additional diagnostic tests to exclude other conditions or to understand the impact of hypoglycemia. These tests insure 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 the kidney function, identify glucose in the urine, and detect the presence of urinary tract infection based on the observation of white blood cells in the urine under the microscope

Fecal flotation to identify the presence of parasites that can cause hypoglycemia, especially in puppies.

ACTH stimulation test to identify hypoadrenocorticism or Addison's disease, an endocrine disorder that occasionally causes hypoglycemia.

Blood concentration of bile acids to evaluate liver function because some animals with liver failure develop hypoglycemia

Serum insulin concentration 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 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.

Abdominal ultrasound exam may be performed to evaluate for the presence of tumors that could cause hypoglycemia. Insulin-producing tumors of the pancreas often are very small and may not be evident on ultrasound examination.

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:

Provide supplemental dextrose by giving corn syrup (Karo® Syrup) on the dog's gums or a 50 percent solution of glucose administered orally. Special care should be taken to be certain the dog has a normal swallowing reflex so as to prevent aspiration of the glucose solution into the lungs. In some dogs, it may be necessary to administer a sterile solution of dextrose by intravenous injection.

Placement of an intravenous catheter and administration of an electrolyte (salt) solution that also contains dextrose. Dogs that have hypoglycemia due to hypoadrenocorticism (Addison's disease) usually are treated with a 0.9 percent sodium chloride (salt) solution.

Patients with low body temperature should be warmed and body temperature should be monitored closely.

Treatment measures after emergency care may include:
Your veterinarian will attempt to identify the underlying cause of hypoglycemia and treat it appropriately. This may include removing the tumor associated with hypoglycemia, treating Addison's disease, feeding dogs small meals before working, providing frequent small meals, and treating body wide infections.

The dog may be hospitalized for observation and treatment of hypoglycemia. Blood glucose concentrations may be checked frequently until the patient has been stabilized.

Feed 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.

Limit exercise to short walks.

Glucocorticoids may be recommended for dogs with hypoglycemia caused by a tumor.

A drug called diazoxide (Proglycem) also may be considered for pets with tumor-induced hypoglycemia.

A drug called Octreotide also can be used for medical treatment of dogs with insulinomas. This drug works by decreasing insulin secretion by the tumor.

Prognosis

Prognosis is dependent on the cause of hypoglycemia. Appropriate diagnosis and treatment of the underlying disorder will assure the best possible prognosis. The prognosis is good in cases of juvenile hypoglycemia, hunting dog hypoglycemia, and Addison's disease.

Dogs with hypoglycemia due to insulinoma generally have a poor prognosis because many of these tumors have metastasized by the time of surgery. With early diagnosis and surgical removal of the tumor however some dogs have lived up to 2 years.

The prognosis for pets 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.

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

Administer as directed any medications prescribed by your veterinarian. Inability to medicate the dog can be a reason for treatment failure.

Feed your dog frequent small meals.

Observe your dog's general activity level and appetite.

Observe your dog for signs of recurrent hypoglycemia, such as lethargy, weakness, staggering, unusual behavior, apparent blindness, muscular twitching, seizures.

Return regularly for blood glucose determinations. Return of hypoglycemia can indicate re-growth of an insulin-producing tumor.

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