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Antiarrhythmic Agents (Prescription) - Cardiac Rhythm Medications for Dogs: Clinically Vetted Top 5 Options in Canada for 2025 (Sotalol, Mexiletine, Amiodarone, Diltiazem, Atenolol)

Published on Thursday, August 21, 2025

Antiarrhythmic drugs manage abnormal heart rhythms in dogs, from atrial fibrillation to ventricular tachycardia, using agents like sotalol, mexiletine, and amiodarone. Selection depends on arrhythmia type, underlying disease, and the drug safety profile for the individual patient. In the Canadian market, owners and veterinarians prefer options that balance proven clinical efficacy, predictable pharmacology, and practical considerations such as provincial availability, cost, and monitoring requirements. Prescription antiarrhythmics appeal to consumers who prioritize quality of life, extended survival, and evidence-based care from general practitioners and specialist cardiologists. For 2025, the top choices reflect drugs with broad clinical use in veterinary cardiology, well-known safety profiles when monitored appropriately, and accessibility through Canadian pharmacies and compounding services.

Quick Menu

1. Best for Ventricular Arrhythmias

2. Best Oral Sodium Blocker

3. Best Potent Multi-class Option

4. Best Rate Control (Calcium Channel)

5. Best Beta-blocker for Dogs

1
BEST FOR VENTRICULAR ARRHYTHMIAS

Sotalol HCl Tablets

Betapace (GSK)

Sotalol combines nonselective beta-blockade with Class III antiarrhythmic properties, making it a go-to market leader for many canine ventricular arrhythmias; its dual mechanism often reduces the need for combination therapy and gives it technical advantages over single‑mechanism drugs. Compared with mexiletine and atenolol, sotalol provides broader rhythm control, and although branded supply carries a higher per‑unit price than some generics, its established clinical track record and consistent tablet formulations make budgeting and dosing more predictable for veterinary practices.

4.2
★★★★☆

  • Stabilizes heartbeat

  • Beta‑block duality

  • Stabilizes heartbeat

  • Beta‑block duality

Review Summary

82%

"Owners report consistent arrhythmia control in many dogs, though some note lethargy, bradycardia, or mild GI upset and the need for periodic ECG/renal monitoring. Generally considered effective and reliable when dose-adjusted by a veterinarian."

  • Heart's calm captain

  • Class III antiarrhythmic with additional beta-blocking properties.

  • Heart's calm captain

  • Class III antiarrhythmic with additional beta-blocking properties.

Increased Safety & Security

Time-Saving Convenience

Sotalol combines nonselective beta-blockade with Class III antiarrhythmic properties, making it a go-to market leader for many canine ventricular arrhythmias; its dual mechanism often reduces the need for combination therapy and gives it technical advantages over single‑mechanism drugs. Compared with mexiletine and atenolol, sotalol provides broader rhythm control, and although branded supply carries a higher per‑unit price than some generics, its established clinical track record and consistent tablet formulations make budgeting and dosing more predictable for veterinary practices.

  • Stabilizes heartbeat

  • Beta‑block duality

  • Heart's calm captain

  • Class III antiarrhythmic with additional beta-blocking properties.

  • Effective for controlling ventricular and some supraventricular arrhythmias in dogs.

  • Stabilizes heartbeat

  • Beta‑block duality

  • Heart's calm captain

  • Class III antiarrhythmic with additional beta-blocking properties.

  • Effective for controlling ventricular and some supraventricular arrhythmias in dogs.

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$60-140 CAD

2
BEST ORAL SODIUM BLOCKER

Mexiletine HCl Capsules

Mexitil (Hikma)

Mexiletine is a well‑established oral Class IB agent favored for maintenance therapy of ventricular tachyarrhythmias in dogs because of its targeted sodium‑channel action and rapid onset. It complements agents like sotalol and amiodarone when sodium‑channel blockade is specifically required, and its widespread availability as a low‑cost generic capsule provides a clear financial advantage for long‑term outpatient management compared with more expensive, heavily monitored drugs.

3.9
★★★☆☆

  • Ventricular stabilizer

  • Rapid sodium block

  • Ventricular stabilizer

  • Rapid sodium block

Review Summary

74%

"Users say mexiletine often reduces ventricular arrhythmias but gastrointestinal side effects (vomiting, diarrhea) and frequent need for compounding affect tolerability. Efficacy is praised by many, but side effects limit long-term use for some pets."

  • Pocket-sized pacer

  • Class IB antiarrhythmic primarily used for ventricular arrhythmias in dogs.

  • Pocket-sized pacer

  • Class IB antiarrhythmic primarily used for ventricular arrhythmias in dogs.

Increased Safety & Security

Time-Saving Convenience

Mexiletine is a well‑established oral Class IB agent favored for maintenance therapy of ventricular tachyarrhythmias in dogs because of its targeted sodium‑channel action and rapid onset. It complements agents like sotalol and amiodarone when sodium‑channel blockade is specifically required, and its widespread availability as a low‑cost generic capsule provides a clear financial advantage for long‑term outpatient management compared with more expensive, heavily monitored drugs.

  • Ventricular stabilizer

  • Rapid sodium block

  • Pocket-sized pacer

  • Class IB antiarrhythmic primarily used for ventricular arrhythmias in dogs.

  • Often used in combination with other agents (e.g., sotalol) for refractory cases.

  • Ventricular stabilizer

  • Rapid sodium block

  • Pocket-sized pacer

  • Class IB antiarrhythmic primarily used for ventricular arrhythmias in dogs.

  • Often used in combination with other agents (e.g., sotalol) for refractory cases.

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$90-220 CAD

3
BEST POTENT MULTI-CLASS OPTION

Amiodarone HCl Tablets

Cordarone (Sanofi)

Amiodarone is a broad‑spectrum, high‑potency antiarrhythmic reserved as a market leader for refractory or complex canine arrhythmias due to its multi‑channel effects across sodium, calcium and potassium currents. Technically superior in difficult cases compared with single‑class agents like diltiazem or mexiletine, it does, however, require more intensive monitoring and carries higher total treatment costs and adverse‑event considerations, making it a specialist option rather than a first‑line maintenance choice.

3.6
★★★☆☆

  • Broad-spectrum control

  • Long-lasting action

  • Broad-spectrum control

  • Long-lasting action

Review Summary

68%

"Amiodarone is reported as potent and effective for refractory arrhythmias, but many owners and vets avoid long-term use because of serious adverse effects and intensive monitoring requirements. Reviews reflect cautious approval when benefits outweigh risks."

  • Potent-but-picky

  • Multi-channel antiarrhythmic with activity across sodium, potassium, and calcium channels and adrenergic blockade.

  • Potent-but-picky

  • Multi-channel antiarrhythmic with activity across sodium, potassium, and calcium channels and adrenergic blockade.

Increased Safety & Security

Time-Saving Convenience

Amiodarone is a broad‑spectrum, high‑potency antiarrhythmic reserved as a market leader for refractory or complex canine arrhythmias due to its multi‑channel effects across sodium, calcium and potassium currents. Technically superior in difficult cases compared with single‑class agents like diltiazem or mexiletine, it does, however, require more intensive monitoring and carries higher total treatment costs and adverse‑event considerations, making it a specialist option rather than a first‑line maintenance choice.

  • Broad-spectrum control

  • Long-lasting action

  • Potent-but-picky

  • Multi-channel antiarrhythmic with activity across sodium, potassium, and calcium channels and adrenergic blockade.

  • Reserved for severe or refractory arrhythmias due to significant long-term toxicity potential.

  • Broad-spectrum control

  • Long-lasting action

  • Potent-but-picky

  • Multi-channel antiarrhythmic with activity across sodium, potassium, and calcium channels and adrenergic blockade.

  • Reserved for severe or refractory arrhythmias due to significant long-term toxicity potential.

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$80-200 CAD

4
BEST RATE CONTROL (CALCIUM CHANNEL)

Diltiazem HCl Tablets

Diltiazem HCl (Teva)

Diltiazem is a calcium‑channel blocker widely recognized as best‑in‑class for supraventricular tachyarrhythmias and AV nodal rate control in dogs, offering predictable hemodynamic effects and compatibility with other rhythm agents. Compared with amiodarone and sotalol, it is often preferred for atrial‑origin tachyarrhythmias because of a favorable side‑effect profile and cost‑effective generic availability, making it an efficient choice for outpatient management of SVT.

4.3
★★★★☆

  • Slows AV conduction

  • Vessel relaxant

  • Slows AV conduction

  • Vessel relaxant

Review Summary

88%

"Diltiazem is widely appreciated for controlling supraventricular tachyarrhythmias with good tolerance in most dogs; occasional hypotension or mild GI signs are reported. Overall users find it effective and well tolerated for rate control."

  • AV-node babysitter

  • Non-dihydropyridine calcium-channel blocker effective for supraventricular tachycardia and ventricular rate control.

  • AV-node babysitter

  • Non-dihydropyridine calcium-channel blocker effective for supraventricular tachycardia and ventricular rate control.

Increased Safety & Security

Diltiazem is a calcium‑channel blocker widely recognized as best‑in‑class for supraventricular tachyarrhythmias and AV nodal rate control in dogs, offering predictable hemodynamic effects and compatibility with other rhythm agents. Compared with amiodarone and sotalol, it is often preferred for atrial‑origin tachyarrhythmias because of a favorable side‑effect profile and cost‑effective generic availability, making it an efficient choice for outpatient management of SVT.

  • Slows AV conduction

  • Vessel relaxant

  • AV-node babysitter

  • Non-dihydropyridine calcium-channel blocker effective for supraventricular tachycardia and ventricular rate control.

  • Available for oral chronic management and can be used IV in acute settings under supervision.

  • Slows AV conduction

  • Vessel relaxant

  • AV-node babysitter

  • Non-dihydropyridine calcium-channel blocker effective for supraventricular tachycardia and ventricular rate control.

  • Available for oral chronic management and can be used IV in acute settings under supervision.

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$25-90 CAD

5
BEST BETA-BLOCKER FOR DOGS

Atenolol Tablets

Tenormin (AstraZeneca)

Atenolol is a selective beta‑1 blocker commonly used for rate control in canine arrhythmias and is valued as a market leader when beta‑selective therapy is desired because of its once‑daily dosing potential and lower risk of pulmonary side effects compared with nonselective agents. Financially and logistically attractive as an inexpensive, widely available option, atenolol is often chosen over pricier agents for straightforward rate control, though it lacks the broad antiarrhythmic spectrum of drugs like amiodarone or sotalol.

4.1
★★★★☆

  • Selective beta-block

  • Lowers heart rate

  • Selective beta-block

  • Lowers heart rate

Review Summary

83%

"Atenolol is commonly used for rate control and is generally well tolerated, with many owners noting improved clinical signs; a minority report lethargy or reduced exercise tolerance. Considered a reliable first-line beta-blocker in veterinary practice."

  • Quiet heart helper

  • Selective beta-1 blocker that reduces heart rate and myocardial oxygen demand.

  • Quiet heart helper

  • Selective beta-1 blocker that reduces heart rate and myocardial oxygen demand.

Increased Safety & Security

Time-Saving Convenience

Atenolol is a selective beta‑1 blocker commonly used for rate control in canine arrhythmias and is valued as a market leader when beta‑selective therapy is desired because of its once‑daily dosing potential and lower risk of pulmonary side effects compared with nonselective agents. Financially and logistically attractive as an inexpensive, widely available option, atenolol is often chosen over pricier agents for straightforward rate control, though it lacks the broad antiarrhythmic spectrum of drugs like amiodarone or sotalol.

  • Selective beta-block

  • Lowers heart rate

  • Quiet heart helper

  • Selective beta-1 blocker that reduces heart rate and myocardial oxygen demand.

  • Useful for supraventricular arrhythmias and as adjunct therapy in some structural heart diseases.

  • Selective beta-block

  • Lowers heart rate

  • Quiet heart helper

  • Selective beta-1 blocker that reduces heart rate and myocardial oxygen demand.

  • Useful for supraventricular arrhythmias and as adjunct therapy in some structural heart diseases.

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$20-70 CAD

What the Research and Guidelines Say

Veterinary cardiology practice in Canada and internationally is guided by a combination of peer-reviewed clinical studies, retrospective case series, and consensus recommendations from specialist bodies. These sources inform which agents are selected for ventricular versus supraventricular arrhythmias, dosing strategies, and monitoring plans. Clinicians emphasize individualized treatment: arrhythmia mechanism, concurrent disease (for example, structural heart disease or systemic illness), and patient tolerance drive the final choice. Monitoring with ECG, periodic blood work, and blood pressure checks is a common recommendation across studies to maximize efficacy and reduce adverse effects.

Sotalol: Multiple veterinary retrospective analyses and clinical reports support sotalol for various ventricular and some supraventricular arrhythmias due to its combined class III and beta-adrenergic blocking properties; it is often recommended when long-term oral control is needed.

Mexiletine: Clinical experience and case series show mexiletine is effective for ventricular arrhythmias in dogs and is commonly used in combination with beta blockers or sotalol when monotherapy is insufficient.

Amiodarone: Evidence supports amiodarone use for refractory or life-threatening arrhythmias; it is effective but has a broader toxicity profile, so guideline-oriented use and close monitoring are emphasized.

Diltiazem: Studies and clinical guidelines indicate diltiazem is helpful for controlling supraventricular tachycardia and rate control in atrial fibrillation, with careful use in dogs with compromised systolic function.

Atenolol: As a selective beta-1 blocker, atenolol is supported by clinical practice for rate control and certain tachyarrhythmias, and it may be chosen for patients where beta blockade is indicated with a favorable safety profile.

Monitoring and safety: Across studies, routine ECG monitoring, baseline and follow-up blood work, and owner education on signs of drug intolerance are recurring recommendations to optimize outcomes.

Guideline support: Canadian clinicians often apply international veterinary cardiology consensus statements and peer-reviewed literature when selecting and monitoring antiarrhythmic therapy.

In Canada in 2025, prescription antiarrhythmic choices for dogs focus on matching the drug to the arrhythmia and the individual patient. The main options discussed here are Sotalol HCl Tablets, Mexiletine HCl Capsules, Amiodarone HCl Tablets, Diltiazem HCl Tablets, and Atenolol Tablets. For many cases that require long-term oral control with a balance of efficacy and tolerability, Sotalol HCl Tablets are often the preferred first-line choice, while Mexiletine or Amiodarone may be chosen for more refractory ventricular arrhythmias and Diltiazem or Atenolol for supraventricular rate control depending on the clinical context. We hope you found what you were looking for; use the site search to refine by drug, condition, or province to expand or narrow your results.

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