# Esmolol: veterinary dose and monograph

> Esmolol is a veterinary cardiovascular drug. An ULTRA-SHORT-acting, cardioselective (β1) beta-blocker given ONLY intravenously (loading bolus then CRI) — its defining feature is a very brief half-life (~a few minutes, via rapid red-cell esterase hydrolysis), so its effect can be… Indications include acute supraventricular tachycardia / rapid ventricular-rate control in atrial fibrillation; intra-operative or crisis sympathetic tachycardia/hypertension; thyrotoxic or phaeochromocytoma-associated tachyarrhythmia (short-term control). This monograph lists 5 reference doses for dogs, cats and horses, each with route, frequency and source.

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

## At a glance

- **Drug class:** Cardiovascular
- **Also known as:** Brevibloc, Miniblock, Esmolol HCl
- **Species with doses:** Dogs, Cats and Horses
- **Routes:** IV
- **Last reviewed:** 1 October 2026

## Indications

- Acute supraventricular tachycardia / rapid ventricular-rate control in atrial fibrillation
- Intra-operative or crisis sympathetic tachycardia/hypertension
- Thyrotoxic or phaeochromocytoma-associated tachyarrhythmia (short-term control)
- Situations needing rapidly titratable, reversible beta-blockade

## Esmolol 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

*Esmolol doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Acute tachyarrhythmia — IV loading | 0.05–0.5 mg/kg | IV | 0.25–0.5 mg/kg over 1–2 min, or 0.05–0.1 mg/kg every 5 min to a 0.5 mg/kg maximum | — |
| Acute tachyarrhythmia — CRI | 10–200 µg/kg/min | IV | CRI, titrated | — |

- Acute tachyarrhythmia — IV loading: Papich 5e: 0.5 mg/kg IV, or 0.05–0.1 mg/kg slowly every 5 min. Plumb’s p.485: 0.25–0.5 mg/kg slow IV over 1–2 min then CRI (Kittleson); SVT 0.05–0.1 mg/kg over 2 min every 5 min to 0.5 mg/kg (Fine; Rush). Omit the loading dose in severe DCM or mitral regurgitation. Continuous ECG and BP.
- Acute tachyarrhythmia — CRI: Papich 5e: 50–200 µg/kg/min after 0.5 mg/kg over 30–60 s. Plumb’s p.485 (Kittleson): 10–200 µg/kg/min; with severe myocardial disease start at 10–20 µg/kg/min without a bolus and titrate every 10 min. Effect ends within minutes of stopping.

### Cats

*Esmolol doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Acute tachyarrhythmia / HCM LVOT trial — IV loading | 0.2–0.5 mg/kg | IV | slow bolus over 1–2 min | — |
| Acute tachyarrhythmia — CRI | 10–200 µg/kg/min | IV | CRI, titrated | — |

- Acute tachyarrhythmia / HCM LVOT trial — IV loading: Plumb’s p.485: 0.25–0.5 mg/kg over 1–2 min (Kittleson); 0.2–0.5 mg/kg over 1 min (Ware). Papich 5e (dogs and cats): 0.5 mg/kg, or 0.05–0.1 mg/kg every 5 min.
- Acute tachyarrhythmia — CRI: Plumb’s p.485: 10–200 µg/kg/min (Kittleson); 25–200 µg/kg/min (Ware). Papich 5e: 50–200 µg/kg/min. Continuous ECG and BP.

### Horses

*Esmolol doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Tachyarrhythmia | 0.2–0.5 mg/kg | IV | 0.2 mg/kg over 1 min, then 0.5 mg/kg over 1 min after 10 min | — |

- Tachyarrhythmia: Papich 5e: 0.2 mg/kg IV over 1 min, then 0.5 mg/kg over 1 min 10 minutes later; CRI 0.5 mg/kg IV followed by 25 µg/kg/min.

## Contraindications

Decompensated congestive heart failure, significant bradyarrhythmia / high-grade AV block, and hypotension. Bronchospastic disease (β2 effects at high doses). Cardiogenic shock. Without continuous ECG/BP monitoring. Known hypersensitivity.

## Adverse effects

- Bradycardia, hypotension (rapidly reversible on stopping)
- Negative inotropy — can worsen heart failure
- Bronchospasm at high doses
- Injection-site reaction (concentrate is irritant)

## Drug interactions

- Calcium-channel blockers (diltiazem/verapamil): additive bradycardia/AV block/myocardial depression
- Other negative chronotropes (digoxin): additive AV slowing
- Sympathomimetics: antagonism
- Other anaesthetics/hypotensives: additive hypotension

## Pregnancy and lactation

Reserve for acute maternal arrhythmia/hypertension when needed; short duration is an advantage. Limited data.

## Monitoring

- Continuous ECG (heart rate/rhythm) and blood pressure — titrate to effect
- Signs of worsening CHF; respiratory status (bronchospasm)
- Infusion rate via pump

## Toxicity and overdose

Overdose causes bradycardia, hypotension, AV block, heart failure and bronchospasm — but because the drug is hydrolysed within minutes, simply STOPPING the infusion reverses effects rapidly (its key safety feature). Glucagon is the antidote for refractory beta-blocker overdose.

Management: STOP the infusion (effects resolve in minutes). For persistent effects: atropine for bradycardia, IV fluids/vasopressors for hypotension, and GLUCAGON for refractory beta-blocker toxicity; treat bronchospasm. Continuous ECG.

## Clinical pearls

- The "on/off switch" beta-blocker — ultra-short half-life lets you titrate rate/arrhythmia control minute-to-minute and back off instantly if the patient decompensates
- IV only (load then CRI) for ACUTE tachyarrhythmia/rate control — not an oral/chronic drug
- Its rapid offset is the safety feature: if bradycardia/hypotension develop, stopping the infusion reverses them within minutes (glucagon for refractory cases)
- Requires continuous ECG/BP monitoring; dilute the 250 mg/mL concentrate before use

## Mechanism of action

A cardioselective β1-adrenergic antagonist that slows sinus rate and AV conduction and reduces contractility, controlling sympathetically-driven tachyarrhythmias and rate. It contains an ester bond that is rapidly hydrolysed by red-cell esterases, giving an extremely short half-life — hence its rapid onset/offset and precise titratability by infusion (and the reason it is IV-only, not an oral drug).

## Formulations and products

- Injection 10 mg/mL
- Concentrate 250 mg/mL (dilute before use)
- Brevibloc / Miniblock — 10 mg/mL; 250 mg/mL concentrate, Injection (CRI) (human-label)

## Storage

Concentrate/premix: 15–30 °C, protect from light; dilute the concentrate before infusion. Do not freeze.

## 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.

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## Frequently asked questions

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

Reference doses for Esmolol in dogs: 0.05–0.5 mg/kg IV 0.25–0.5 mg/kg over 1–2 min, or 0.05–0.1 mg/kg every 5 min to a 0.5 mg/kg maximum (Acute tachyarrhythmia — IV loading); 10–200 µg/kg/min IV CRI, titrated (Acute tachyarrhythmia — CRI). Confirm against the label and the patient before use.

### What is the dose of Esmolol for cats?

Reference doses for Esmolol in cats: 0.2–0.5 mg/kg IV slow bolus over 1–2 min (Acute tachyarrhythmia / HCM LVOT trial — IV loading); 10–200 µg/kg/min IV CRI, titrated (Acute tachyarrhythmia — CRI). Confirm against the label and the patient before use.

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

Reference doses for Esmolol in horses: 0.2–0.5 mg/kg IV 0.2 mg/kg over 1 min, then 0.5 mg/kg over 1 min after 10 min (Tachyarrhythmia). Confirm against the label and the patient before use.

### When should Esmolol not be used?

Decompensated congestive heart failure, significant bradyarrhythmia / high-grade AV block, and hypotension. Bronchospastic disease (β2 effects at high doses). Cardiogenic shock. Without continuous ECG/BP monitoring. Known hypersensitivity.

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

Bradycardia, hypotension (rapidly reversible on stopping); Negative inotropy — can worsen heart failure; Bronchospasm at high doses; Injection-site reaction (concentrate is irritant).

## 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.