Exocrine Pancreatic Insufficiency

The pancreas is a relatively small, yet vital organ that lies along the base of the stomach and the upper portion of the small intestine called the duodenum. It serves two primary metabolic purposes: its endocrine function regulates blood-glucose release and uptake, and its exocrine function produces digestive enzymes that are released through the pancreatic ducts into the duodenum. The enzymes aid in breaking down common dietary constituents such as fat, protein, and carbohydrates into lesser molecules that can be absorbed through the intestinal wall into the bloodstream. There are not two distinct sections of the pancreas responsible for these functions; rather, the endocrine and exocrine related cells are diffused throughout the entire organ. Pancreatic endocrine dysfunction can lead to diabetes mellitus or hypoglycemia (low blood sugar levels); whereas exocrine pancreatic insufficiency (EPI) causes malabsorption of nutrients. Symptoms of EPI include persistent diarrhea, weight loss despite an increased appetite, and referred problems with other organ systems due to malnutrition.

Exocrine pancreatic insufficiency is caused by destruction of the related cells within the pancreas and can stem from several causes. In acinar atrophy, the acinar cells in the pancreas that store digestive enzymes become shriveled and dysfunctional. This condition is the most common cause of EPI in dogs. It is thought to have a genetic determinant, and breeds predisposed include Rough-Coated Collies and German Shepherd. Acinar atrophy can occur at any age, but generally develops in young adults.

Another cause of EPI in dogs and cats is chronic pancreatitis. Pancreatitis simply means inflammation of the organ, but does not suggest a reason. Pancreatitis may indiscriminately affect both the endocrine and exocrine functions of the pancreas, and it may lead to diabetes and EPI concurrently. Usually, symptoms of EPI do not occur until 90% or more of the enzyme-producing cells have been damaged. Miniature Schnauzers are at an increased risk of developing chronic pancreatitis.

Pancreatitis can become chronic after an acute episode. It may be caused by dietary indiscretion or occasionally, a bacterial infection of the pancreas. A fatty meal like meat trimmings or drippings may trigger the onset of illness. Vomiting and diarrhea are the primary symptoms, except in cats, which may have a relatively silent form of the disease. The most common cause of EPI in cats is due to chronic pancreatitis.

Pancreatic cancer is the rarest cause of EPI, yet carries the gravest prognosis. The cancer may be isolated in the pancreas or may have metastasized or spread from another organ system.

The digestive enzymes that are deficient in animals with exocrine pancreatic insufficiency include amylase, lipase, protease, and trypsin. Each serves to help breakdown specific components in the diet so that they may be absorbed and utilized for energy, growth, and tissue repair. Gray, greasy diarrhea results from maldigestion of the nutrients; and the animal will begin to lose weight despite a compensatory increased appetite. Poor hair-coat health evident as dry, flaky skin and increased shedding is a common secondary symptom to malnutrition.

After ruling out other possible causes of diarrhea, a diagnosis of EPI is confirmed with a blood test called a trypsin-like immunoreactivity test, or TLI. This test measures the blood level of the digestive enzyme trypsin, which is normally detectable in very small amounts in healthy animals. Dogs and cats with EPI will have virtually no measurable blood levels of the enzyme.

The treatment for EPI must include addressing any underlying cause for pancreatic changes. Then, dietary supplementation of the digestive enzymes is used to help aid digestion and absorption of nutrients. There are specific products formulated for dogs and cats (Pancrezyme, Viokase-V) available as powders that are mixed with the pet’s food. Tablet forms do not seem to work as consistently as powders. In addition, an antacid may be given to help reduce the stomach’s acid production and increase the available enzyme entering the intestinal tract. Furthermore, a low fiber, low to moderate fat, highly digestible food will help the pet absorb more nutrients and as a result, gain weight. There are “prescription” type diets that your veterinarian will recommend.

Adjunct therapies for EPI patients include intestinally active antibiotics to reduce bacterial overgrowth occurring as a result of maldigestion. Probiotics (lactobacillus acidophilus) can help to reestablish the normal bacterial flora in the gut. Cobalamin (vitamin B12) and folate (vitamin B9) supplementation is also required where bacteria have depleted the normal sources of these important vitamins. Cobalamin deficiency is associated with anemia and neuropathy; and even pets on supplementation enzymes may require ongoing B12 injections. Both cobalamin and folate blood tests are usually combined with the TLI test in the diagnostic blood-chemistry panel.

Supplementation will be required for the life of the patient. In most cases, patients respond very well to this treatment.

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