Inflammatory bowel disease (IBD) is the most frequent cause of chronic diarrhea and vomiting in the cat. Cats from multiple cat households have a higher incidence of diarrhea than cats from single cat households. Currently, diagnosis requires intestinal biopsy. This study will investigate the applicability of less invasive immunologic tests for IBD as used in humans. IBD is due either to an abnormal immune response against normal intestinal microbes or to a normal immune response against abnormal microbes. The second part of this study will investigate the possible role of pathogenic types of fecal microbes in chronic IBD of cats. With this information, management options based on anti-microbials and anti-inflammatory drugs can be developed.