A poodle with clinical signs of colorectal disease was diagnosed as pneumatosis coli. In this dog, hypoadrenocorticism and immune-mediated hemolytic anemia concurred. Pneumatosis coli is one of the emphysematous gastrointestinal diseases. The etiology is unknown but mechanical, pulmonary and bacterial theories have been proposed. In pneumatosis coli, gas accumulates within submucosal or subserosal layer of colon or rectum, so intramural radiolucent gas is observed on abdominal radiographs. In this dog, intramural gas accumulation occurred in cecum. Definitive diagnosis was based on radiographic findings and an underlying cause was not elicited. Pneumatosis coli should be included into differential diagnosis for nonspecific colorectal signs.