Chronic gastrointestinal disease is commonly encountered in dogs in general practice, and diarrhoea is a frequent manifestation. Causes include conditions such as idiopathic inflammatory bowel disease, food allergy and neoplasia, although they can often be a challenge to diagnose. Using current best evidence, this presentation will review the diagnosis and management of selected chronic gastrointestinal diseases in dogs. We will also discuss the reasons for, and consequences of, cobalamin deficiency and consider data to support oral cobalamin use.