Gastrointestinal problems in dogs can have many causes. These include poor diet, stress, infections, parasite infestations, medications, allergies, food intolerances and diseases such as gastritis or colitis. Ingestion of foreign bodies or toxins can also lead to digestive disorders. It is important that pet owners consult a veterinarian at the first sign of gastrointestinal problems to clarify the cause and initiate appropriate treatment.