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Atenolol

Prescription

Beta-1 selective adrenergic blocker

Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team

Species

Dog, Cat

Brands

3 available

Interactions

5 documented

Formulations

Mechanism of action

Selectively blocks beta-1 adrenoceptors in the heart, reducing heart rate, contractility, and myocardial oxygen demand

At a glance

Class

Beta-1 selective adrenergic blocker

Schedule

Prescription

Storage

Store below 25°C, protect from light and moisture

Dosing

🐕

Dog

Supraventricular tachycardia, ventricular arrhythmias

Dose

0.25–1 mg/kg

Route

Frequency

BID

Max dose

50 mg/dose; 100 mg/day

Duration: Long-term; taper on discontinuation

🐈

Cat

Hypertrophic cardiomyopathy (HCM)

Dose

6.25–12.5 mg/cat

Route

Frequency

BID

Max dose

12.5 mg/dose; 25 mg/day

Duration: Long-term

Hyperthyroidism (adjunct — rate control)

Dose

6.25–12.5 mg/cat

Route

Frequency

BID

Max dose

12.5 mg/dose; 25 mg/day

Duration: Until methimazole achieves euthyroid state

Educational reference only

This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Tablet — 3

Strength

25mg

Available in India

Strength

50mg

Available in India

Strength

100mg

Available in India

Storage

Store below 25°C, protect from light and moisture

Safety

Absolute contraindications — do not use

Bradycardia / AV block
Beta-blockers worsen pre-existing conduction abnormalities
Uncompensated heart failure
Negative inotrope may precipitate failure — stabilise first

Use with caution

Asthma / bronchospasm
Beta-1 selective but at higher doses loses selectivity — may cause bronchospasm
Diabetes
May mask tachycardia of hypoglycaemia

Adverse effects

Common

Bradycardia

Lethargy

Hypotension

Serious

AV block

Acute heart failure exacerbation

Bronchospasm

Monitoring parameters

Heart rateBlood pressureECGExercise tolerance

Educational reference only

Interactions

Major — 1

Diltiazem

major

Both suppress AV conduction and myocardial contractility; combined use risks severe bradycardia and heart block

Management: Use combination with extreme caution. Monitor ECG. May be intentional for rate control in refractory cases.

Moderate — 4

Pimobendan

moderate

Pimobendan is a positive inotrope; beta-blockers have negative inotropic effects. Opposing cardiac actions.

Management: Generally avoid concurrent use in systolic dysfunction. May be acceptable in specific arrhythmia cases with cardiology guidance.

Amlodipine

moderate

Additive antihypertensive effect; risk of excessive hypotension and bradycardia

Management: Common combination for feline hypertension/HCM. Start low, titrate slowly, monitor blood pressure.

Terbutaline

moderate

Atenolol (cardioselective beta-1) has minimal beta-2 blockade at therapeutic doses — less bronchospasm risk than propranolol. However, at higher doses, selectivity is lost.

Management: Use lowest effective atenolol dose. Monitor respiratory function. If bronchospasm worsens, discontinue beta-blocker.

Phenylpropanolamine

moderate

PPA (alpha/beta agonist) + beta-blocker: unopposed alpha vasoconstriction. Blood pressure elevation.

Management: Monitor blood pressure closely when combining. Use lowest effective PPA dose.

Educational reference only

Brands

International

Tenormin

AstraZeneca

India

Aten

Zydus

Atekind

Mankind

FAQs

Frequently asked questions

›What is Atenolol?

Atenolol is a beta-1 selective adrenergic blocker used in pets. Selectively blocks beta-1 adrenoceptors in the heart, reducing heart rate, contractility, and myocardial oxygen demand

›What is Atenolol used for in pets?

Atenolol is used in veterinary medicine for: Supraventricular tachycardia, ventricular arrhythmias; Hypertrophic cardiomyopathy (HCM); Hyperthyroidism (adjunct — rate control).

›What is the Atenolol dose for dogs?

For dogs, Atenolol is typically dosed as follows — Supraventricular tachycardia, ventricular arrhythmias: 0.25–1 mg/kg PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What is the Atenolol dose for cats?

For cats, Atenolol is typically dosed as follows — Hypertrophic cardiomyopathy (HCM): 6.25–12.5 mg/cat PO BID; Hyperthyroidism (adjunct — rate control): 6.25–12.5 mg/cat PO BID. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.

›What are the side effects of Atenolol?

Common: Bradycardia, Lethargy, Hypotension. Serious (call your vet immediately): AV block, Acute heart failure exacerbation, Bronchospasm.

›Does Atenolol need a prescription?

Yes. Atenolol is a prescription medication and should only be administered under veterinary supervision.

›When should Atenolol not be used?

Do not use Atenolol if: Bradycardia / AV block; Uncompensated heart failure.

Educational reference only

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

Plumb's Veterinary Drug Handbook
Withrow & MacEwen's Small Animal Clinical Oncology
Merck Veterinary Manual
NRC Nutrient Requirements of Dogs and Cats
Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

ASPCA Animal Poison Control Center Guidelines
AAHA Diabetes Management Guidelines
ASPCA Poison Control Guidelines
RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

EPIC Study (J Vet Intern Med 2016)
JVIM FAT CAT Study

Regulatory & approvals — 1

CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

Washington State University VCPL MDR1 Database