This comprehensive review focuses first on the principles of nutritional management of canine and feline gastrointestinal diseases by detailing the process of nutritional assessment of the patient, the current diet, feeding management, environment, and reassessment and monitoring once the chosen dietary strategy has been implemented. Then a detailed review of the relevant nutritional strategies for the management of acute gastroenteritis, adverse reaction to food, chronic inflammatory enteropathy, intestinal lymphangiectasia, and feline constipation is provided.