Detomidine is an imidazole derivative and α2-adrenergic agonist, used as a large animal sedative, primarily used in horses. It is usually available as the salt detomidine hydrochloride. It is a prescription medication available to veterinarians sold under the trade name Dormosedan..
Detomidine is a sedative with analgesic properties.[1] α2-adrenergic agonists produce dose-dependent sedative and analgesic effects, mediatated by activation of α2 catecholamine receptors, thus inducing a negative feedback response, reducing production of excitatory neurotransmitters. Due to inhibition of the sympathetic nervous system, detomidine also has cardiac and respiratory effects and an antidiuretic action
A profound lethargy and characteristic lowering of the head with reduced sensitivity to environmental stimuli (sounds, etc.) are seen with detomidine. A short period of in-coordination is characteristically followed by immobility and a firm stance with front legs spread. Following administration there is an initial increase in blood pressure, followed by bradycardia and second degree atrioventricular block (this is not pathologic in horses). The horse commonly sweats to excess, especially on the flanks and neck. Other side effects reported include pilo erection (hair standing erect), ataxia, salivation, slight muscle tremors, and (rarely) penile prolapse.