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. Signs and symptoms
Loss of pancreatic enzymes leads to maldigestion and malabsorption, which may in turn lead to:
anemia (Vitamin B12, iron, folate deficiency)
bleeding disorders (Vitamin K malabsorption)
edema (hypoalbuminemia)
fatigue
flatulence and abdominal distention (bacterial fermentation of unabsorbed food)
hypocalcemia
metabolic bone disease (Vitamin D deficiency)
neurologic manifestation
steatorrhea
weight loss

Causes
In humans, the most common causes of EPI are chronic pancreatitis and cystic fibrosis, the former a longstanding inflammation of the pancreas altering the organs normal structure and function that can arise as a result of malnutrition, heredity, or (in the Western world especially), behaviour (alcohol use, smoking), and the latter a recessive hereditary disease most common in Europeans and Ashkenazi Jews where the molecular culprit is an altered, CFTR-encoded chloride channel. According to WebMD, "Crohns disease and celiac disease can also lead to EPI in some people". In children, another common cause is Shwachman-Bodian-Diamond syndrome, a rare autosomal recessive genetic disorder resulting from mutation in the SBDS gene. Diagnosis
The three main tests used in considering a diagnosis of EPI are: fecal elastase test, fecal fat test, and a direct pancreatic function test. The latter is a limitedly used test that assesses exocrine function in the pancreas by inserting a tube into the small intestine to collect pancreatic secretions.
Diagnosis and treatment
The most reliable test for EPI in dogs and cats is serum trypsin-like immunoreactivity (TLI);  a low value indicates EPI. Fecal elastase levels may also be used for diagnosis in dogs.In dogs, the best treatment is to supplement the animals food with dried pancreatic extracts. There are commercial preparations available, but chopped bovine pancreas from the butcher can also be used. (Pork pancreas should not be used because of the rare transmission of pseudorabies). Symptoms usually improve within a few days, but lifelong treatment is required to manage the condition. A rare side-effect of use of dried pancreatic extracts is oral ulceration and bleeding.Because of malabsorption, serum levels of cyanocobalamin (vitamin B12) and tocopherol (vitamin E) may be low. 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.Cyanocobalamin deficiency is very common in cats with EPI because about 99 percent of intrinsic factor (which is required for cyanocobalamin absorption from the intestine) is secreted by the pancreas. In dogs, this figure is about 90 percent, and only about 50 percent of dogs have this deficiency.Cats may suffer from Vitamin K deficiencies. If there is bacterial overgrowth in the intestine, antibiotics should be used, especially if treatment is not working. In dogs failing to gain weight or continuing to show symptoms, modifying the diet to make it low-fiber and highly digestible may help.