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U.S. Department of Health and Human Services

Animal & Veterinary

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FDA Veterinarian Newsletter March/April 2000 Volume XV, No II

By Germaine Connolly, D.V.M.

Ketamine hydrochloride officially became a schedule III controlled substance on August 12, 1999. Schedule III labels will appear on commercial containers after April 15, 2000. Control of ketamine was considered necessary due to years of abuse, diversion, and robberies related to both the human and veterinary products. Ketamine is approved for anesthesia or restraint in cats and restraint in subhuman primates by intramuscular injection. The dissociative cataleptoid state, somatic analgesia, and altered consciousness are rapidly induced. To eliminate many of the typical side effects associated with its use (extreme muscle tone, exuberant spontaneous movement, violent recovery, and occasional convulsions), ketamine is combined with sedatives and tranquilizers; its use as a monoanesthetic is limited.

For those veterinarians who are unwilling or unable to make use of scheduled drugs, there are FDA-approved veterinary alternatives. Propofol, an injectable anesthetic for intravenous administration in dogs and cats is approved for induction and maintenance of anesthesia. Its rapid effect and rapid recovery make it suitable for procedures requiring restraint, and anesthesia can be extended by repeated doses and concomitant sedation. Volatile anesthetics such as isoflurane (approved in dogs and horses), sevoflurane (approved in dogs), and halothane (approved in dogs, cats and horses) are labeled for the induction and maintenance of anesthesia.

Many unscheduled approved veterinary sedatives and tranquilizers are available to provide restraint and analgesia. Alpha2-adrenergic agonists such as xylazine (approved for dogs, cats, horses), detomidine (approved for horses), and medetomidine (approved for dogs) can be administered intramuscularly, provide deep sedation and their effects are reversible using alpha2-antagonists. Acepromazine, a phenothiazine neuroleptic tranquilizer, is approved for use in dogs, cats, and horses.

Veterinarians using the above unscheduled approved veterinary drugs can adequately provide restraint and anesthesia to their patients. These resources when combined with schedule III controlled substances like ketamine and tiletamine/zolazepam and schedule II narcotics provide an ample variety of veterinary approved anesthetic and preanesthetic agents.