Exocrine Pancreatic Insufficiency - contd.
The pancreas serves two major functions. One of these, the endocrine function, is to secrete hormones, particularly insulin. The second major function of the pancreas is to secrete digestive enzymes; this is known as its exocrine function. As the name implies, exocrine pancreatic insufficiency involves abnormalities in the secretion of digestive enzymes. Since enzymes are not available to help digest nutrients, the nutrients cannot be used normally by the body. In addition to the lack of proper digestion of nutrients, exocrine pancreatic insufficiency is accompanied by structural and functional changes in the tissue lining of the small intestine that further impair nutrient absorption.
The most common causes of exocrine pancreatic insufficiency are pancreatic acinar atrophy, or PAA, and chronic pancreatitis. PAA is a disorder that usually affects young adult dogs, particularly German shepherds. Common symptoms include diarrhea and weight loss despite a normal or increased appetite. PAA is not known to occur in cats. Chronic pancreatitis is more commonly a cause of EPI in cats and older dogs. Animals with EPI due to chronic pancreatitis often have diabetes mellitus, since the endocrine portion of the pancreas may also be affected. The symptoms of EPI due to chronic pancreatitis are the same as those caused by pancreatic acinar atrophy. However, additional symptoms like intermittent vomiting and decreased appetite due to pancreatitis, or increased thirst and urination associated with diabetes mellitus, are present as well.
At the present time, the most important diagnostic test for EPI is the measurement of trypsin-like immunoreactivity, or TLI, on a blood sample drawn after a 12-hour fast. Once the diagnosis is confirmed, the main treatment is the oral administration of enzyme replacements, which are usually taken with each meal. Additional treatments, discussed in the treatment section, may be appropriate.
