Exocrine pancreatic insufficiency (EPI) is the inability to properly digest food due to a lack of digestive enzymes made by the pancreas. EPI is found in humans afflicted with cystic fibrosis and Shwachman-Diamond Syndrome, and is common in dogs. EPI is caused by a progressive loss of the pancreatic cells that make digestive enzymes; loss of digestive enzymes leads to maldigestion and malabsorption of nutrients from normal digestive processes. Chronic pancreatitis is the most common cause of EPI in humans and cats. In dogs, the most common cause is by pancreatic acinar atrophy, arising as a result of genetic conditions, a blocked pancreatic duct, or prior infection.