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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
3

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
PO
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
PO
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
PO
Frequency
BID
Max dose
12.5 mg/dose; 25 mg/day
Duration: Until methimazole achieves euthyroid state

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

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.

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.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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 →