Xylazine
Xylazine hydrochloride
Also known as: Rompun · AnaSed · Sedazine · Cervizine · Chanazine · Gemini · Nerfasin · Sedaxylan · Virbaxyl · Xylacare · Xylapan · Xylazine HCl · Bay-Va-1470 · Xylazine hydrochloride
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (2)
Evidence only — not for automatic calculation
Preanesthetic agent (extra-label)
Preanesthetic agent (extra-label): 0.2 – 1 mg/kg IV, IM, or SC 20
Governing clinical context (3)
- NOTE: A reversal agent should always be on hand; reversal of sedative effects also reverses analgesic effects.
- NOTE: Most clinicians prefer using newer alpha-2 agonists (eg, dexmedetomidine) that have a greater selectivity for the alpha-2 adrenergic receptor.
- Do not store above 30°C (86°F). Some manufacturers state to store at 20°C to 25°C (68°F-77°F) and permit excursions up to 40°C (104°F).
Evidence only — not for automatic calculation
Analgesic adjunct (extra-label)
Analgesic adjunct (extra-label): 0.05 – 0.5 mg/kg IV, IM, or SC
Governing clinical context (3)
- NOTE: A reversal agent should always be on hand; reversal of sedative effects also reverses analgesic effects.
- NOTE: Most clinicians prefer using newer alpha-2 agonists (eg, dexmedetomidine) that have a greater selectivity for the alpha-2 adrenergic receptor.
- Do not store above 30°C (86°F). Some manufacturers state to store at 20°C to 25°C (68°F-77°F) and permit excursions up to 40°C (104°F).
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Xylazine is a potent alpha-2 adrenergic agonist widely used in veterinary medicine for its sedative, analgesic, and muscle relaxant properties. It is also frequently utilized as a reliable emetic (to induce vomiting) in cats.
Clinical Pearl: There is profound species variability in sensitivity to xylazine. Ruminants are exquisitely sensitive, requiring approximately 1/10th the dose used in horses to achieve the same effect. Conversely, swine are highly resistant and require 20-30 times the ruminant dose.
While it provides excellent visceral analgesia (especially in horses), its use in small animals is often reserved for young, healthy patients due to its significant cardiovascular depressant effects, including bradycardia, arrhythmias, and decreased cardiac output. It is not FDA-approved for use in food-producing animals, though it is sometimes used extra-label with strict withdrawal times.
Mechanism of action
Xylazine stimulates presynaptic and postsynaptic alpha-2 adrenergic receptors in the central and peripheral nervous systems.
- Sedation & Analgesia: Activation of central alpha-2 receptors → decreased release of norepinephrine and dopamine → profound CNS depression and analgesia.
- Muscle Relaxation: Centrally mediated inhibition of intraneuronal transmission of impulses in the CNS.
- Cardiovascular Effects (Biphasic): Initial stimulation of peripheral alpha-1 and alpha-2 receptors → transient vasoconstriction and hypertension → subsequent central sympatholytic effect → hypotension, bradycardia, and potentially second-degree AV block. Cardiac output can decrease by up to 30%.
- Emesis: Stimulates the chemoreceptor trigger zone (CRTZ), particularly in cats.
- Endocrine/Renal: Decreases insulin release → transient hyperglycemia. Decreases ADH production → polyuria (especially in ruminants).
Safety & warnings
Contraindications
- Animals receiving epinephrine
- Active ventricular arrhythmias
- Preexisting cardiac dysfunction
- Hypotension or shock
- Respiratory dysfunction
- Severe hepatic or renal insufficiency
- Preexisting seizure disorders
- Severely debilitated animals
- Last trimester of pregnancy (particularly in cattle)
- Dehydrated or debilitated ruminants
- Urinary tract obstruction (ruminants)
- Intra-arterial injection (may cause severe seizures and collapse)
- Cardiovascular disease
- Systemic disease affecting cardiovascular performance
- Geriatric patients
- Pregnant animals
- Diabetic animals
- Patients receiving sympathomimetic amines
- Conditions where vomiting is contraindicated (e.g., foreign body, raised intraocular pressure)
- Ingestion of strong acids, alkalis, or volatile/oily organic products
- Unconscious or seizing animals, or those with a reduced cough reflex
Adverse effects
- Emesis (especially in cats, occasionally dogs)
- Muscle tremors
- Bradycardia with partial A-V block
- Reduced respiratory rate and tidal volume
- Sudden movement or kicking in response to sharp auditory stimuli (especially horses)
- Increased urination (cats, cattle)
- Bloat from aerophagia (dogs, cattle)
- Sweating (horses)
- Salivation, ruminal atony, regurgitation, and diarrhea (cattle)
- Premature parturition (cattle)
- Transient hypertension followed by hypotension
- Decreased mucociliary clearance (horses)
- Cardiovascular depression (bradycardia, arrhythmias)
- Vomiting (especially in cats)
- Diuresis (suppression of ADH secretion)
- Transient hyperglycaemia (decreased insulin secretion)
- Mydriasis
- Decreased intraocular pressure
- Increased uterine motility
Precautions
Use extreme caution in ruminants due to high sensitivity; ensure correct product concentration (20 mg/mL vs 100 mg/mL). Horses may appear deeply sedated but can still kick violently in response to sudden noises (auditory stimuli). May induce premature parturition in cattle. Can inhibit GI motility; use cautiously in patients with intestinal impactions. Use cautiously in horses during the vasoconstrictive phase of laminitis. Brachycephalic dogs and horses with upper airway disease may develop dyspnea.
Drug interactions
Potential for additive hypotensive effects; use cautiously in animals susceptible to hemodynamic complications.
Prolonged sedation and gastrointestinal stasis possible.
Additive CNS depression. Dosages of these agents may need to be reduced.
May induce the development of ventricular arrhythmias (with or without concurrent halothane).
May cause colic-like clinical signs in horses; concurrent use should be avoided.
Significantly reduces the dose of all other anaesthetic agents required to maintain anaesthesia.
Increased risk of severe cardiac arrhythmias.
Monitoring
- Level of anesthesia/analgesia
- Respiratory function (rate, depth, tidal volume)
- Cardiovascular status (heart rate, rhythm, blood pressure)
- Hydration status (especially if polyuria is present)
- Heart rate and rhythm (ECG)
- Respiratory rate and depth
- Blood glucose (in susceptible patients)
Pharmacokinetics
Half-life
Absorption
Rapid following IM injection, but bioavailabilities are incomplete and variable (40-48% in horses, 17-73% in sheep, and 52-90% in dogs).
Distribution
Widely distributed; crosses the blood-brain barrier to exert central effects.
Metabolism
Undergoes hepatic metabolism.
Elimination
Metabolites are excreted primarily in the urine. Not detected in milk of lactating dairy cattle at 5 and 21 hours post-dose.
Overdose
In the event of an accidental overdosage, profound CNS and respiratory depression, hypotension, and cardiac arrhythmias may occur. Seizures have also been reported.
- Reversal Agents: Alpha-2 antagonists such as yohimbine, atipamezole, and tolazoline can be used alone or in combination to reverse the effects of xylazine and speed recovery times.
- Supportive Care: Mechanical respiratory support and respiratory stimulants (e.g., doxapram) may be required to treat severe respiratory depressant effects.
Available products
Formulations
- Injection: 20 mg/mL
- Injection: 100 mg/mL
- Injection: 300 mg/mL (for deer and elk)
- Injectable: 20 mg/ml solution
Veterinary
- Xylazine Injection: 20 mg/mL in 20 mL vials
- Xylazine Injection: 100 mg/mL in 50 mL vials
- Xylazine Injection: 300 mg/mL (Cervizine, for deer and elk)
- Chanazine 20 mg/ml solution for injection
- Nerfasin 20 mg/ml solution for injection
- Rompun 20 mg/ml solution for injection
- Sedaxylan 20 mg/ml solution for injection
- Virbaxyl 20 mg/ml solution for injection
- Xylacare 20 mg/ml solution for injection
- Xylapan 20 mg/ml solution for injection
Regulatory status
POM-V
POM-V
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Do not store above 30°C (86°F). Reportedly physically compatible in the same syringe with acepromazine, buprenorphine, butorphanol, chloral hydrate, and meperidine. Compounded mixtures of ketamine, acepromazine, and xylazine ('KAX') are stable for at least 180 days if stored at room temperature in the dark.
Client information
Xylazine is a potent sedative and pain-relieving medication used to calm animals for procedures or as part of an anesthetic protocol.
- Vomiting: It is very common for cats (and sometimes dogs) to vomit shortly after receiving this drug. This is an expected effect and is sometimes the primary reason the drug is given (e.g., if your pet ate something toxic).
- Recovery: Your pet may be groggy, uncoordinated, or sleepy for a few hours after the procedure. Keep them in a quiet, safe, and comfortable environment until they are fully awake.
- Startle Reflex: Even if an animal (especially a horse) appears deeply asleep, sudden loud noises can cause them to startle or kick violently. Always move quietly around sedated animals.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.