Drugs are legitimately used to treat a variety of medical conditions in horses. These may include parasiticides (e.g. wormers), vaccinations and therapeutics such as anti-inflammatories. However, when drugs are used to prevent a horse from running at full potential (e.g., tranquilizers), or to enhance performance (e.g., narcotics), such use is not allowed.
Sometimes, even worse abuses are detected. In Kentucky, sponges were inserted deep in the nasal passages of horses to compromise their breathing and alter their race performance . Such abuse can have potentially life-threatening consequences.
1. Mundy GD. (2000). Equine welfare. Racing. J Amer Vet Med Assoc, 216(8), 1243-1246.