Alfaxalone: veterinary dose and monograph

At a glance

Drug class

Sedative / anaesthetic

Also known as

Alfaxan

Species with doses

Dogs, Cats, Pigs, Rabbits and Ferrets

General dose range

1–5 mg/kg IV to effect (induction) or CRI — check the species tables for the indication

Routes

IV, IM

Last reviewed

1 October 2026

Indications

• Induction of general anaesthesia (dog / cat)
• Total intravenous anaesthesia maintenance (CRI)
• IM sedation in fractious cats / small patients

Alfaxalone dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• IV induction: Papich 5e: 1.5–4.5 mg/kg IV if not premedicated; 0.2–3.5 mg/kg after premedication — titrate over 60 s; top-ups about 1–1.2 mg/kg (up to 2) per 10 minutes. Plumb’s p.49: 1–2 mg/kg IV slowly over 20–30 s; UK label 2–3 mg/kg. Apnoea possible — have intubation and oxygen ready.
• Maintenance CRI: Papich 5e: 6–10 mg/kg/h IV, suitable alongside other anaesthetic agents. Recovery after alfaxalone maintenance is longer than after inhalant.

Cats

• IV induction: Papich 5e: 2.2–10 mg/kg IV (average 4 mg/kg) unpremedicated, 1–4 mg/kg after premedication; titrate over 60 s with 2 mg/kg top-ups. Plumb’s p.49: 2–5 mg/kg IV slowly (label 5 mg/kg); total 5–7 mg/kg for short procedures such as castration, 8–12 mg/kg for longer ones. CRI (Papich): 1.7 mg/kg IV then 7–10 mg/kg/h.
• IM sedation (fractious): Papich 5e: 2–3 mg/kg IM or IV for mild sedation, can be mixed with butorphanol 0.2 mg/kg in one syringe. Large IM volumes — split sites.
• Deep sedation / light anaesthesia (IM): Plumb’s p.49 (Alfaxan-CD RTU label, NZ): 5–10 mg/kg IM into the quadriceps; 10 mg/kg gives deep sedation or light anaesthesia for venepuncture or minor procedures (e.g. abscess drainage).

Pigs

• Miniature/pet pig — induction / sedation: Carpenter Exotic Animal Formulary 6th ed, Table 12-4 (p.662): miniature pigs 5–6 mg/kg IM, or 6 mg/kg IV; with dexmedetomidine 10 µg/kg IM gives smooth sedation (onset 3–4 min). Venous access in conscious pigs is difficult — IM route practical.

Rabbits

• Anaesthesia induction: Plumb's p.50: rabbits 6–9 mg/kg IV, or 9 mg/kg IM. ⚠ Apnoea is common — provide oxygen by facemask and be ready to intubate; prefer IM/premedicated induction unless confident with intubation. Alfaxalone is one of the better-tolerated rabbit induction agents.

Ferrets

• Anaesthesia induction / sedation: Carpenter's 6th ed (Ferret table): 5 mg/kg IV for induction; 5–15 mg/kg IM for sedation. Provide oxygen; monitor for apnoea.

Contraindications

Use reduced doses in cardiovascular / respiratory compromise and in shock. Always titrate to effect; have airway support ready. Caesarean use possible but titrate carefully.

Adverse effects

• Dose-dependent respiratory depression / apnoea (especially with rapid injection)
• Hypotension at higher doses
• Excitement / paddling during recovery if unpremedicated or recovered in a noisy area

Drug interactions

• Additive CNS / respiratory depression with opioids, benzodiazepines, alpha-2 agonists and inhalants — reduce the induction dose after premedication
• No significant metabolic drug interactions reported

Pregnancy and lactation

Crosses the placenta but is rapidly cleared; widely used for caesarean induction — titrate to the lowest effective dose and ventilate the dam.

Monitoring

• Respiratory rate / apnoea — preoxygenate and be ready to ventilate
• Blood pressure
• Recovery quality (recover in a quiet area)

Toxicity and overdose

Overdose or a rapid bolus causes apnoea, hypoventilation and hypotension. There is no antidote; the short duration means support until redistribution is usually sufficient.

Management: Secure the airway, give oxygen and assisted / mechanical ventilation for apnoea, and IV fluids ± vasopressors for hypotension until the patient lightens (rapid clearance).

Clinical pearls

• Give the induction dose slowly over ~60 seconds and titrate — a fast bolus is the usual cause of apnoea
• Premedicate and recover patients somewhere quiet; rough recoveries are almost always under-premedication
• The ability to dose IM makes it a friend for cats you cannot place a catheter in awake

Mechanism of action

Neuroactive (synthetic) steroid anaesthetic. Positively modulates GABA-A receptors in the CNS, enhancing chloride conductance to produce dose-dependent sedation, hypnosis and anaesthesia. Rapidly redistributed and metabolised (non-cumulative), giving fast, clear recoveries.

Formulations and products

• Alfaxan 10 mg/mL injection
• Alfaxan (Jurox / Dechra) — 10 mg/mL, IV / IM injection

Storage

Store at 15–25 °C. The preservative-free formulation is single-use — discard opened vials per label; preserved (multidose) versions allow up to ~28 days.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other sedatives and anaesthetics

• Acepromazine
• Azaperone
• Detomidine
• Dexmedetomidine
• Diazepam
• Etomidate
• Guaifenesin (GGE)
• Isoflurane

Frequently asked questions