This talk discusses from a clinical perspective, general considerations for the use of non-inferiority studies used to establish the effectiveness of a new animal drug in veterinary medicine. The talk will focus on regulatory and clinical study design concerns. Each type of control group used in a clinical trial including placebo control, active control and historical control, has unique considerations. From a clinical perspective, considerations for the use of an active control are animal welfare concerns, study recruitment, bias, choice of the active control, constancy assumption, bio-creep, assay sensitivity, sample size, and how changes in standard of care need to be taken into consideration. The draft guidance "Active Controls in Studies to Demonstrate the Effectiveness of a New Drug for Use in Companion Animals" will be discussed from a clinical perspective.