When veterinarians include drug testing in a prepurchase exam, their goal is to make sure the horse is being evaluated in its natural, untreated state — i.e. not under the influence of sedatives that calm behavior or NSAIDs that reduce pain and mask lameness. In this excerpt from Ask TheHorse Live, Wendy Krebs, DVM, of Bend Equine Medical Center, in Oregon, describes how veterinarians do this and when they recommend buyers utilize these tests during the purchasing process.