The sugar that the brain and other organs use for energy is called glucose and is found in the bloodstream. Glucose is formed during the digestion of foods and can be stored in the liver as glycogen.
Hypoglycemia simply means a low blood sugar. When the brain is deprived of the energy that it needs, seizures can occur. Other symptoms of hypoglycemia include weakness, tremors, irritability, lethargy, incoordination, nervousness and hunger.
The mechanisms responsible for hypoglycemia are excess insulin from insulin overdose or insulinoma, reduction of hormones needed for maintenance of normal serum glucose, reduced ability of the liver to produce glucose or store glycogen, excessive utilization or reduced nutritional intake.
Hypoglycemia is diagnosed based on clinical symptoms of hypoglycemia, blood glucose concentrations that show low blood sugar and the fact that symptoms disappear when glucose is administered to the patient. If the diagnosis is positive for hypoglycemia your vet may want to do further testing to determine the cause of the hypoglycemia.
Some of the specific causes of hypoglycemia are:
Young dogs - Liver shunts, congenital hypothyroidism, transient juvenile hypoglycemia and glycogen storage diseases
Adult onset - insulinoma, liver disease, hypoglycemia of hunting dogs and intestinal diseases that reduce nutritional absorption with weight loss
Unassociated with age - bacteremia, hypopituitarism, Addison's Disease, drug reactions and toxin exposure
Small breed puppies are particularly susceptible to transient juvenile hypoglycemia because their liver is not able to store sufficient amounts of glycogen. As the name implies, this is transient and usually resolves when the puppy reaches 4 months. Until then feeding small amounts every three hours will usually prevent any hypoglycemic attacks.
Chastain, C. B, Clinical
Endocrinology of Companion Animals
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Last Updated August 2009