Prescription pillsWhat is Atenolol?

Atenolol is classified as a beta blocker. Its main purpose is to block receptors on the heart that respond to stress or excitement. This type of drug helps control heart rate, decreases the incidence of certain arrhythmias, and is commonly used as a treatment for feline
hypertrophic cardiomyopathy. It has overall effects on improving oxygen use by the heart muscle.


  • Feline hypertrophic cardiomyopathy
  • Canine subvalvular aortic stenosis (SAS)
  • Ventricular premature beats and ventricular tachycardia
  • Atrial premature beats and supraventricular tachycardia
  • Systemic hypertension (high blood pressure)
  • Hyperthyroidism

Adverse Effects

[please contact CVCA should any of these symptoms be noted]

  • Low heart rate resulting in signs of low blood pressure such as lethargy, depression, and weakness
  • Must be used with caution in patients with decreased heart muscle strength and/or congestive heart failure, as symptoms may be worsened
  • Needs to be used with caution in patients with airway disease or asthma
  • May have some effect on blood sugar control in diabetic patients
  • Cannot be stopped suddenly, as this can result in a rebound rapid heart rate. Patients need to be weaned off this class of drug

Client Information

  • Can be given with food
  • Can be given with other medications to treat heart disease when instructed by CVCA
  • Dosing is usually once or twice daily by mouth. When giving this medication once daily, morning dosing is preferred especially in cats
  • Can be given in pill form or reformulated into a flavored liquid
  • Do not skip doses or stop giving this medication as heart rate could quickly rise again
  • Please contact CVCA if your pet requires anesthesia, as dose adjustments may be necessary

Interactions with Other Drugs

  • Increased risk for low heart rate or hypotension when combined with other drugs (acepromazine, amlodipine, diltiazem, enalapril/ benazepril)
  • The doctors at CVCA have already taken this into account, however, please feel free to contact us to discuss any concurrent medications your pet may be prescribed

Dosage Forms

  • Atenolol tablets – 25mg, 50mg, 100mg pill sizes
  • Name Brand: Tenormin®


Drug Handouts