Page 835 - Small Animal Internal Medicine, 6th Edition

CHAPTER 49 Disorders of the Endocrine Pancreas 807

BOX 49.1 BOX 49.2
VetBooks.ir Causes of Hyperglycemia in Dogs and Cats Causes of Hypoglycemia in Dogs and Cats

Diabetes mellitus*
Stress, aggression, excitement, nervousness, fright* β-Cell tumor (insulinoma)*
Primary and metastatic neoplasia
Postprandial (within 2 hours of consuming diets Hepatocellular carcinoma, hepatoma*
containing monosaccharides, disaccharides, propylene Leiomyosarcoma, leiomyoma*
glycol, corn syrup) Hemangiosarcoma
Hyperadrenocorticism* Carcinoma (mammary, salivary, pulmonary, gastric,
Acromegaly (cat) small intestine, renal, splenic)
Diestrus (bitch) Leukemia
Pheochromocytoma (dog) Plasmacytoma
Pancreatitis Melanoma
Exocrine pancreatic neoplasia Hepatobiliary disease*
Chronic kidney disease Portosystemic shunts
Head trauma Chronic fibrosis, cirrhosis
Drug therapy* Hepatic necrosis (toxins)
Glucocorticoids Sepsis*
Progestins Severe canine babesiosis
Megestrol acetate Septic peritonitis
Dextrose-containing fluids* Hypoadrenocorticism*
Parenteral nutrition solutions* Idiopathic hypoglycemia*
Neonatal hypoglycemia
*Common cause. Juvenile hypoglycemia (especially toy breeds)
Hunting dog hypoglycemia
Exocrine pancreatic neoplasia
always lower than actual glucose values as determined by Pancreatitis
benchtop methods, and this may result in an incorrect diag- Chronic kidney disease
nosis of hypoglycemia. In contrast, an erroneous reading Hypopituitarism
with the AlphaTRAK glucometer (Abbott Laboratories), Severe polycythemia
designed for use in diabetic dogs and cats, can be high or Hepatic enzyme deficiencies
low compared with actual glucose values. Finally, labora- Von Gierke’s disease (type I glycogen storage
disease)
tory error may result in an incorrect value. It is wise to Cori’s disease (type III glycogen storage disease)
confirm hypoglycemia by determining the blood glucose Severe malnutrition
concentration from a second blood sample and using bench- Prolonged storage of whole blood*
top methods before embarking on a search for the cause of Iatrogenic*
hypoglycemia. Insulin overdose
Sulfonylurea therapy
Clinical Features Ethylene glycol ingestion
Clinical signs of hypoglycemia usually develop when the Xylitol ingestion
blood glucose concentration is less than 45 mg/dL, although Alpha lipoic acid
this can be variable. The development of clinical signs Dried chicken jerky treats
depends on the severity and duration (acute versus chronic) Artifact*
of hypoglycemia and the rate of decline in the blood glucose Portable blood glucose–monitoring devices
Laboratory error
concentration. Clinical signs are a result of neuroglycopenia-
and hypoglycemia-induced stimulation of the sympathoad- *Common cause.
renal nervous system. Neuroglycopenic signs include
seizures; weakness; collapse; ataxia; and, less commonly,
lethargy, blindness, bizarre behavior, and coma. Signs of insulin, stimulate hepatic glucose secretion, and promote an
increased secretion of catecholamines include restlessness, increase in the blood glucose concentration.
nervousness, and muscle fasciculations.
Depending on the cause, the signs of hypoglycemia may Diagnostic Approach
be persistent or intermittent. The hallmark clinical sign of Hypoglycemia should always be confirmed before diagnostic
hypoglycemia (i.e., seizures) tends to be intermittent, regard- studies are begun to identify the cause. Careful evaluation of
less of the cause. Dogs and cats usually recover from hypo- the animal’s history, physical examination findings, and
glycemic seizures within a couple of minutes as a result of results of routine blood and urine tests (i.e., complete blood
activation of counterregulatory mechanisms (e.g., secretion count [CBC], serum biochemistry panel, urinalysis) usually
of glucagon and catecholamines) that block the effects of provides clues to the underlying cause. Hypoglycemia in the