Xylazine

Alpha-2 adrenergic agonist for sedation, analgesia, and preanesthetic medication in horses, cattle, dogs, and cats; colic analgesia. Alpha-2 adrenergic agonist (xylazine HCl). Mechanism: agonist at alpha-2A and alpha-2B adrenergic receptors → inhibits presynaptic norepinephrine release and postsynaptic adrenergic signaling in the CNS → dose-dependent sedation, muscle relaxation, and analgesia (better for visceral than somatic pain). Initial peripheral vasoconstriction then bradycardia. Species-sensitive; horses require ~10× lower dose than cattle. Reversed by yohimbine. Key information DEA Schedule III. Alpha-2 agonist. Reversal: yohimbine (dogs, horses) or atipamezole (small animals). Cattle: 10x more sensitive — reduce dose significantly. Do not use as sole analgesic for painful procedures. Causes vomiting in cats — useful diagnostic tool. Avoid in animals with cardiac disease.

IV (horses): administer slowly into jugular vein — full effect in 2–5 min. IM (horses): onset 10–20 min. Cattle: administer IM at 1/10th equine dose. Dogs/cats: IM or SQ. Have reversal agent (yohimbine or atipamezole) available. Keep horse's head elevated during and after sedation. Store at room temperature; protect from light. If a dose is missed This medication is administered by a veterinarian or veterinary staff in a clinical setting. Missed doses are managed by your veterinary team — contact your veterinarian to reschedule.

Cardiovascular: bradycardia, AV block, initial hypertension then hypotension. Respiratory: rate/tidal volume reduction. GI: decreased motility (colic in horses, bloat in cattle). Diuresis (polyuria). Sweating (horses). Ataxia. Penile prolapse (horses — stallions). Hypoxemia (horses in lateral recumbency). Cattle: 10× more sensitive than horses — use cattle-specific doses. Reversible with yohimbine.

For animals Cattle: 10× more sensitive than horses — use cattle-specific dose (typically 0.05–0.1 mg/kg IM). Horses: do not use in animals with cardiac disease or severe bradycardia. GI: ileus — do not use in horses with suspected obstruction. Monitor respiratory function. Reversal: yohimbine (dogs/cats/horses); atipamezole (dogs/cats). Not approved for use in food-producing animals. Use with caution in pregnant animals. For people handling this medication Wear gloves when handling. Potent alpha-2 agonist sedative — even small amounts can cause dangerous sedation and cardiovascular depression in humans. Avoid skin contact and accidental injection. If accidentally self-injected or if significant skin contact occurs, seek emergency medical attention immediately. Do not drive or operate machinery after handling. Keep out of reach of children.

This is a veterinary emergency. Overdose causes profound sedation, respiratory depression, and cardiovascular collapse. Reversal agent (yohimbine) is available and must be administered by veterinary staff immediately.