Gastrointestinal neoplasms in dogs and cats (Proceedings)CVC IN WASHINGTON, D.C. PROCEEDINGS - Apr 01, 2009Primary gastrointestinal (GI) neoplasia is an important differential diagnosis for a dog or cat with vomiting or diarrhea, especially chronic vomiting or diarrhea, anorexia and weight loss, particularly animals that are middle-aged and older.