What is "equithesin"

Equithesin is the proprietary name for a commercial mixture of chloral hydrate, magnesium sulfate and pentobarbital sodium that was used as a general anesthetic in horses. Equithesin was administered intravenously to effect and for many years was the most commonly used injectable anesthetic in horses. Newer anesthetic agents such as injectable barbiturates, alpha-2 agonists, cyclohexylamines, and inhalants gradually replaced Equithesin. The drug has been off the market and unavailable for decades.