Abstract
Animal models provide a vehicle for understanding basic biological questions. Through the use of animal models, adequate control of experimental design is possible so that rigorous experiments can be performed to test a hypothesis. In the case of testing therapeutic mechanisms, it is important to select a model that is most analogous to the clinical setting so that observations can be readily transferred to clinical studies for validation. In mechanistic studies of Mycobacterium bovis strain (bacille Calmette-Guérin) therapy for bladder cancer, the orthotopic animal model most closely mimics the clinical treatment of bladder cancer.