Canine and feline inflammatory bowel disease (IBD) denotes a heterogeneous group of idiopathic, chronic, relapsing inflammatory disorders of the gastrointestinal tract that are immunologically-mediated. While their exact etiologies remain unknown, results from basic science and clinical studies suggest that interplay between genetic factors and enteric bacteria are crucial for disease development, owing to abnormal host responses directed against the commensal microbiota. Key clinical signs include vomiting, diarrhea and weight loss, and histopathologic lesions of inflammation may involve the stomach, small intestine, or colon. Recent advances in molecular tools, disease activity indices, and biomarker development now permit objective assessment of IBD severity at diagnosis and in response to various therapies. Treatment of IBD involves both dietary and pharamacologic interventions as well as therapeutic manipulation of the enteric microbiota through the use of antibiotics and soluble fiber (prebiotic) supplements. Here we provide a comprehensive overview on the etiopathogenesis, clinical features, diagnosis strategies, current treatment recommendations, and outcomes from veterinary studies in dogs and cats with IBD. We also offer scientific comparison between human and canine IBD.