A five-month-old male intact French bulldog, presented to Cornell University’s Hospital for Animals, Internal Medicine Service, on February 4, 2009 with a history of bloody diarrhea. The puppy had a history of bloody diarrhea since time of purchase. Traditional therapy for diarrhea was not successful. Colonic biopsies were taken and a diagnosis of histiocytic ulcerative colitis was made. The dog was treated with an eight week course of enrofloxacin.