Tiletamine is a dissociative anesthetic and pharmacologically classified as an NMDA receptor antagonist. It is related chemically and pharmacologically to other anesthetics in this family such as ketamine and phencyclidine. Tiletamine hydrochloride exists as odourless white crystals. It is used in veterinary medicine in the compound product Telazol (tiletamine/zolazepam, 50 mg/ml of each in 5 ml vial) as an injectable anesthetic for use in cats and dogs. It is sometimes used in combination with xylazine (Rompun) to tranquilize large mammals such as polar bears and wood bison. Telazol is the only commercially available tiletamine product in the United States. It is contraindicated in patients of an ASA score of III or greater and in animals with CNS signs, hyperthyroidism, cardiac disease, pancreatic or renal disease, pregnancy, glaucoma, or penetrating eye injuries.