# Amiodarone: veterinary dose and monograph

> Amiodarone is a veterinary cardiovascular drug. Potent, broad-spectrum (predominantly class III) antiarrhythmic reserved for SERIOUS refractory ventricular and supraventricular tachyarrhythmias — e.g. Indications include refractory ventricular tachycardia / frequent VPCs (when sotalol/mexiletine fail); refractory atrial fibrillation / supraventricular tachycardia (rate/rhythm control); life-threatening arrhythmia in cardiomyopathy (Dobermann, Boxer). This monograph lists 4 reference doses for dogs and horses, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/amiodarone · Last reviewed: 2026-10-01

## 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

*Amiodarone doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Refractory arrhythmia — loading | 10–15 mg/kg | PO | q12h × ~7 days (loading) | — |
| Refractory arrhythmia — maintenance | 5–10 mg/kg | PO | q24h | — |
| Emergency conversion (IV, in-hospital) | 5 mg/kg | IV | slow IV over 10+ min | — |

- 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

*Amiodarone doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Atrial fibrillation / VT conversion (CRI) | 0.83–5 mg/kg/h | IV | 5 mg/kg/h × 1 h, then 0.83 mg/kg/h × 23 h | — |

- 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

> **Caution:** 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

> **Caution:** 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](https://vetmasterji.com/drugs/amlodipine)
- [Atenolol](https://vetmasterji.com/drugs/atenolol)
- [Benazepril](https://vetmasterji.com/drugs/benazepril)
- [Captopril](https://vetmasterji.com/drugs/captopril)
- [Carvedilol](https://vetmasterji.com/drugs/carvedilol)
- [Digoxin](https://vetmasterji.com/drugs/digoxin)
- [Diltiazem](https://vetmasterji.com/drugs/diltiazem)
- [Dobutamine](https://vetmasterji.com/drugs/dobutamine)

## Frequently asked questions

### What is the dose of Amiodarone for dogs?

Reference doses for Amiodarone in dogs: 10–15 mg/kg PO q12h × ~7 days (loading) (Refractory arrhythmia — loading); 5–10 mg/kg PO q24h (Refractory arrhythmia — maintenance); 5 mg/kg IV slow IV over 10+ min (Emergency conversion (IV, in-hospital)). Confirm against the label and the patient before use.

### What is the dose of Amiodarone for horses?

Reference doses for Amiodarone in horses: 0.83–5 mg/kg/h IV 5 mg/kg/h × 1 h, then 0.83 mg/kg/h × 23 h (Atrial fibrillation / VT conversion (CRI)). Confirm against the label and the patient before use.

### When should Amiodarone not be used?

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.

### What are the side effects of Amiodarone in animals?

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).

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.