[16] The exocrine pancreas is a portion of this organ that contains clusters of ducts (acini) producing bicarbonate anion, a mild alkali, as well as an array of digestive enzymes that together empty by way of the interlobular and main pancreatic ducts into the duodenum (upper small intestine).

[17] The hormones cholecystokinin and secretin secreted by the stomach and duodenum in response to distension and the presence of food in turn stimulate the production of digestive enzymes by the exocrine pancreas.

[18] The alkalization of the duodenum neutralizes the acidic chyme produced by the stomach that is passing into it; the digestive enzymes serve to catalyze the breakdown of complex foodstuffs into smaller molecules for absorption and integration into metabolic pathways.

EPI results from progressive failure in the exocrine function of the pancreas to provide its digestive enzymes, often in response to a genetic condition or other disease state, resulting in the inability of the animal involved to properly digest food.

[24] The latter is a less used test that assesses exocrine function in the pancreas by inserting a tube into the small intestine to collect pancreatic secretions.

[25] EPI is treated with pancreatic enzyme replacement therapy (PERT) called pancrelipase, which is used to break down fats (via a lipase), proteins (via a protease), and carbohydrates (via amylase) into units that can be digested.

[26] Pancrelipase is typically porcine derived in the prescription products although over-the-counter options also exist, including those made with plants and other non-porcine materials.

[30] In dogs, EPI is most common in young German Shepherds, and in Finland Rough Collies,[31] and is inherited.

[36] In dogs, symptoms include weight loss, poor hair coat, flatulence, increased appetite, coprophagia, and diarrhea.

These may be supplemented, although since cyanocobalamin contains the toxic chemical cyanide, dogs that have serious cobalamin issues should instead be treated with hydroxocobalamin or methylcobalamin.

In dogs failing to gain weight or continuing to show symptoms, modifying the diet to make it low-fiber and highly digestible may help.