Amiodarone: veterinary dose and monograph

At a glance

Drug class

Cardiovascular

Also known as

Cordarone, Tachyra, Amipace

Species with doses

Dogs and Horses

General dose range

5–15 mg/kg PO q12–24h (loading then maintenance) — check the species tables for the indication

Routes

PO, IV

Last reviewed

1 October 2026

Indications

• Refractory ventricular tachycardia / frequent VPCs (when sotalol/mexiletine fail)
• Refractory atrial fibrillation / supraventricular tachycardia (rate/rhythm control)
• Life-threatening arrhythmia in cardiomyopathy (Dobermann, Boxer)

Amiodarone 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

• Refractory arrhythmia — loading: Papich 5e: ventricular arrhythmias 10–15 mg/kg q12h PO for 1 week, then 5–7.5 mg/kg q12h for 2 weeks; atrial fibrillation 15 mg/kg for 5 days then 10 mg/kg/day; Boxer/Doberman 200 mg per dog q12h for a week. Plumb’s p.75: 10 mg/kg PO q12h for a week (Meurs; Smith); 10–20 mg/kg once daily for 5–7 days (Saunders). Load in hospital where possible.
• Refractory arrhythmia — maintenance: Papich 5e: maintenance 7.5 mg/kg q24h (Boxer/Doberman 200 mg once daily). Plumb’s p.75: 8 mg/kg once daily, reduced to 5 mg/kg after 6 months (Meurs 2005); 5 mg/kg q12h (Smith); 5–10 mg/kg once daily (Saunders). Monitor liver enzymes, thyroid and CBC; hepatotoxicity and neutropenia reported.
• Emergency conversion (IV, in-hospital): Papich 5e: 5 mg/kg slowly IV over 10 minutes — use cautiously; rapid IV causes hypotension and anaphylactoid reactions. ECG and blood pressure monitoring.

Horses

• Atrial fibrillation / VT conversion (CRI): Papich 5e and Plumb’s p.75 (De Clercq 2006): 5 mg/kg/h for 1 h, then 0.83 mg/kg/h for 23 h (Plumb’s: then 1.9 mg/kg/h for 30 h); stop when converted or if side effects (weight shifting, hind-limb weakness) appear. Oral absorption is poor and not recommended.

Contraindications

High-grade AV block / severe bradyarrhythmia without pacing. Significant hepatic or thyroid disease (and it perturbs both). Iodine hypersensitivity (it is iodine-rich). Concurrent strong negative chronotropes or QT-prolonging drugs. Pregnancy. Known hypersensitivity.

Species-specific warnings

Dogs: Dobermanns may be predisposed to amiodarone hepatotoxicity/hypersensitivity — monitor liver values closely and use the lowest effective dose.

Adverse effects

• GI upset, anorexia (common, dose-limiting orally)
• Hepatotoxicity (raised liver enzymes — monitor)
• Thyroid dysfunction (hypo- or hyper-; iodine load)
• Bradycardia, hypotension; rare pulmonary infiltrates/fibrosis
• Anaphylactoid/hypotensive reactions with rapid IV (vehicle)

Drug interactions

• Digoxin: amiodarone raises digoxin levels (reduce digoxin ~50 %, monitor)
• Other QT-prolonging/antiarrhythmic drugs: additive proarrhythmia
• Warfarin: markedly potentiated anticoagulation
• CYP3A substrates (cyclosporine, etc.): increased levels (CYP inhibition)
• Beta-blockers/CCBs: additive bradycardia/hypotension

Pregnancy and lactation

Contraindicated/avoid in pregnancy — iodine load causes fetal thyroid effects.

Monitoring

• ECG/Holter (efficacy, QT, bradyarrhythmia)
• Liver enzymes and thyroid panel at baseline and periodically (hepato-/thyroid toxicity)
• Blood pressure (especially with IV use)
• Digoxin/warfarin levels if co-administered; respiratory signs

Toxicity and overdose

Chronic toxicity dominates: hepatotoxicity, thyroid dysfunction, GI signs, and (less commonly in dogs than people) pulmonary toxicity; plus bradycardia/hypotension and proarrhythmia. Acute IV toxicity is hypotension/anaphylactoid reaction from rapid infusion. The very long half-life means effects and interactions persist for weeks.

Management: No specific antidote. Supportive — manage bradycardia (atropine, possibly pacing), hypotension (fluids/vasopressors), and arrhythmia; discontinue and support liver/thyroid. Effects are prolonged due to tissue accumulation. Treat anaphylactoid IV reactions (slow/stop infusion, antihistamine, fluids).

Clinical pearls

• A heavy-hitter reserved for refractory, life-threatening arrhythmias when sotalol/mexiletine/diltiazem have failed
• Demands monitoring: check liver enzymes and thyroid function before and during therapy (it deranges both)
• Give IV SLOWLY — rapid infusion causes hypotension/anaphylactoid reactions
• Halve concurrent digoxin and watch warfarin closely — major interactions, and effects linger for weeks (long half-life)

Mechanism of action

A multi-class antiarrhythmic: predominantly class III (blocks potassium channels, prolonging action-potential duration and refractoriness), with additional sodium-channel block (class I), beta-blockade (class II) and calcium-channel block (class IV). This broad electrophysiologic action suppresses diverse re-entrant and automatic arrhythmias. Its iodine content and tissue accumulation underlie the thyroid/organ toxicities and very long half-life.

Formulations and products

• 100 mg tablet
• 200 mg tablet
• Injection 50 mg/mL
• Cordarone — 100 / 200 mg tablet; 50 mg/mL injection, Tablet / injection (human-label)
• Tachyra / Amipace — 100 / 200 mg tablet, Tablet (human-label)

Storage

Tablets: 15–30 °C, protect from light. Injection: protect from light; dilute and infuse slowly (incompatibilities — follow label).

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 cardiovascular drugs

• Amlodipine
• Atenolol
• Benazepril
• Captopril
• Carvedilol
• Digoxin
• Diltiazem
• Dobutamine

Frequently asked questions