Like many mammalian organs, the pancreas is two organs in one. It has an endocrine (hormone) function, producing insulin, which allows cells to utilize glucose for energy. It also has an exocrine (secretive) function, producing enzymes that aid in the breakdown of fat and other major components of food so that they can be absorbed through the intestinal wall, as well as other factors important in digestion and absorption of nutrients.
Famed veterinary gastroenterologist Dr. Jorg M. Steiner defines exocrine pancreatic insufficiency (EPI) as “a syndrome, which is caused by insufficient synthesis and secretion of digestive enzymes by the exocrine portion of the pancreas, leading to insufficient activity of digestive enzymes in the lumen of the small intestine.”
Dogs with EPI seem to be genetically programmed to defective and degenerating acinar cells, the pancreatic cells that are supposed to produce the missing digestive enzymes. The “poster child” of pancreatic acinar atrophy (PAA) is the young to young-adult German Shepherd dog, although the condition occurs in many other breeds, as well.
Cats, on the other hand, follow the path of humans to EPI. Chronic inflammation of the gland, termed pancreatitis, results in scarring and destruction of both enzyme-producing and hormone-producing cells. Thus, the pancreatitis patient may experience both EPI and diabetes mellitus.
Just as we are born with more kidney and liver capability than we need, called reserve function, the exocrine pancreas is similarly endowed with extra. In humans, it is known that about 90% of the exocrine function of the pancreas must be lost before a person exhibits clinical signs of EPI.
Digestive malfunction occurs via two mechanisms. The first is that pancreatic enzymes are necessary for efficient breakdown of large food molecules. Second, the enzymes are needed to transport nutrients across the wall of the intestine and into lymphatics and the bloodstream.
One result is that the EPI patient will have an unusually-large stool volume, as well as a particularly bad stool odor due to undigested food components, especially fat. In addition, weight loss is common because of nutrient loss. Bacteria thrive on the excess nutrients in the GI tract and overgrowth of those bacteria is a common finding. Failure to absorb vitamins, such as B12 and folate, can lead to other nutritional deficiencies.
Definitive diagnosis comes from a blood sample. Cats and dogs have separate tests for serum trypsin-like immunoreactivity (cTLI and fTLI). Readings below a known specific level in the bloodstream diagnose EPI with reliability.
Enzyme replacement is the treatment of choice in dogs, cats and people. Commercially-available extracts of the pancreases of cattle and swine can be mixed with meals and greatly improve the digestive-tract status of most EPI patients. Products available for pets include Viokase® and Pancrezyme®, among others. Dr. Steiner says, “The clinical impression in dogs and cats that powder is more effective than tablets, capsules, and especially enteric-coated products has also been substantiated in human patients with EPI.” Your veterinarian will give you a starting dose, which may require adjustment as therapy proceeds.
Food should be thoroughly mixed with enzymes before feeding. Dr. Steiner opines that preincubation of the food with enzymes is unnecessary.
Food choice is important, also. Certain forms of fiber interfere with pancreatic enzyme function. Foods should be low in insoluble or non-fermentable fiber. Your veterinarian can help you choose the best food for your pet’s total needs.
Rarely, some dogs may experience oral bleeding when eating food treated with enzymes. A slight reduction in the dosage and moistening the food usually resolves that problem.
If fat absorption is insufficient in the face of proper enzyme administration, an oral antacid may be prescribed by your pet’s doctor. Doing so may raise the pH of stomach acid and reduce gastric destruction of lipase in the supplement.
Vitamin B12 (cobalamin) and folate (the ester form of folic acid, vitamin B9) may be deficient in EPI patients. Therefore, blood levels of these nutrients must be measured on a regular and recurring basis.
Dr. Steiner reminds us that patients failing to respond may be suffering from intestinal bacterial overgrowth, concurrent inflammatory bowel disease (especially cats) or other gastrointestinal maladies.
See you next week, Dr. Randolph.