Chronic intestinal protein loss is a sign of failure of digestive function that may result from severe acute or chronic inflammatory lesions or from a disruption of chyle absorption and intestinal lymph flow. While the exact mechanisms leading to intestinal protein loss have not been elucidated in the dog, the three basic mechanisms defined for humans with protein-losing enteropathy (PLE) likely also apply to canine PLE. It is frequently associated with severe chronic idiopathic inflammatory enteropathies such as inflammatory bowel disease (IBD) or with idiopathic intestinal lymphangiectasia in specific breeds. Protein loss may result from: 1) erosive or ulcerative mucosal lesions causing secondary exudation of proteins; 2) lymphatic dysfunction causing leakage of protein-rich lymph into the intestinal lumen; 3) mucosal changes disturbing the mucosal barrier, causing abnormal permeability and protein leakage into the lumen; or 4) a combination of all three of the previously listed conditions. This presentation will focus on chronic intestinal disorders associated with intestinal protein loss in dogs and the dietary and medical treatments for this condition.