Doping in the horse racing industry has been a problem ever since it began. Different drugs are used to increase the chance of winning, losing, and even masking the use of other drugs. Some drugs are used only to enhance performance, but there are also some that are used therapeutically that have the capability to alter the performance of the horse. The three drugs that will be discussed in this review are NSAIDs, Furosemide, and Acepromazine. NSAIDs are used to control pain and inflammation, but in doing so can allow the horse to run at full capacity even if there is an underlying injury such as a sprain. Furosemide is a diuretic that therapeutically is used to decrease the chance of developing exercise-induced pulmonary hemorrhage, but can also mask the use of performance enhancing drugs. Finally, acepromazine is a sedative that can be used to calm a horse who is overly excitable but can also be used to decrease the performance of a horse in order to alter the winner and can have an impact on those that are betting. The pharmacology of these three drugs will be further explored into how they exert their effect and the potential harm they can cause.