Hypoglycemia

Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO

BASIC INFORMATION a blood count, biochemistry profile, insulin assays, chest and Description abdominal x-rays, abdominal ultrasound, specialized tests for liver Hypoglycemia refers to a low concentration of glucose (sugar) in and adrenal function, aspiration or biopsy of any masses found, the blood or serum. and surgical exploration of the abdomen (especially for a sus- Causes pected insulinoma). Hypoglycemia has many different causes. • Neonatal and juvenile hypoglycemia. Puppies and kittens, as TREATMENT AND FOLLOW-UP well as toy-breed dogs, have inadequate stores of glycogen Treatment Options (which can be converted to glucose) in the liver. They also may have physical problems that make it hard for them to maintain Symptomatic treatment of low blood sugar is important. If the ani- normal blood sugar, such as poor nutrition, diarrhea, intestinal mal is conscious, it can be offered food. If the animal is uncon- parasites, or hypothermia. scious, intravenous glucose is given. Intravenous fluids and • Overdosage of insulin in diabetic animals antiseizure drugs may be needed for animals that do not respond • Ingestion of hypoglycemic drugs or agents. In cats, this may to glucose alone. Maintenance of body temperature and supportive involve overdosage with glipizide or glyburide. In dogs, inges- care are given until the animal recovers. tion of xylitol in sugar-free gum can cause hypoglycemia. Specific treatment is started once the underlying cause is • Hypoadrenocorticism (low levels of cortisol hormone) determined: • Insulinoma (a tumor of the cells of the pancreas that secrete insulin) • Frequent feedings may prevent neonatal, juvenile, and exer- • Other malignant tumors. Some tumors have the ability to tional hypoglycemia. secrete substances that act like insulin. Examples include • Continuous or intermittent oral or injectable glucose is given malignant tumors of the liver, kidneys, and fat cells. for ingestion of hypoglycemic agents, insulin overdosage, sep- • Liver failure sis, or liver failure. • Overwhelming infection (sepsis) • Treatment of insulinoma and other tumors may involve surgi- • Exertional hypoglycemia. Hypoglycemia may develop in hunt- cal removal. Oral diazoxide is used in some cases of insuli- ing, sled-dog, and other breeds under extreme working condi- noma, because it helps maintain blood sugar levels. tions. It arises from depletion of stored glycogen in the liver • Steroids such as prednisone may be helpful in cases of hypo- and increased demand for blood sugar. adrenocorticism, insulinoma, or other tumors. • Inherited glycogen storage diseases, which are congenital defects • No effective therapy has been developed for glycogen storage that affect normal liver function. They have been documented in diseases. the Norwegian forest cat, Akita, English springer spaniel, German Follow-up Care shepherd dog, Lapland (Swedish Lapphund), and others. Blood glucose assays are repeated until the animal and glucose Clinical Signs blood levels have returned to normal. Other vital signs are moni- Signs are often neurologic in nature, with the severity proportional tored frequently in animals with seizures. Following insulinoma to how fast, how long, and how low the blood sugar drops. Mild surgery, blood sugar may rise dramatically and may require tran- signs include weakness, tremors, increased appetite, mental dull- sient insulin injections. ness, and bizarre behavior. Serious signs include collapse, sei- Prognosis zures, stupor or coma (unconscious), and blindness. Animals with neonatal, juvenile, or exertional hypoglycemia and animals that have ingested hypoglycemic agents or received too Diagnostic Tests much insulin frequently respond well to supplemental glucose. Because glucose assays can be affected by the storage of samples and Animals with severe seizures, however, carry a poorer prognosis. other factors, the test is often repeated if it is initially low. Repeated Animals with insulinoma may do well following complete surgical evidence of low blood sugar confirms the presence of hypoglycemia. resection, but metastasis is common within 1 year after surgery. In some cases, the origin of the low blood sugar is suspected based Prognosis for animals with other tumors depends on whether on the animal’s age, size, and circumstances (such as a puppy that the tumor can be effectively treated. Sepsis and liver failure became hypothermic during shipping, a hunting dog that collapsed at are both difficult to treat, and recovery from these diseases is the end of the day, a dog seen swallowing a pack of sugar-free gum, or variable. No treatment is available for inherited glycogen storage a diabetic cat that did not eat breakfast after insulin was given). diseases, and most animals deteriorate over months. For more In other cases, the cause is not obvious, and an exhaustive information on hypoadrenocorticism, see the client handout on search must be undertaken to find the origin. Such tests include Hypoadrenocorticism (Addison’s Disease) .