(Tenormin® is another name for this medication.) 

Use: Atenolol is used to treat heart disease in cats and dogs. Atenolol works by slowing the heart and making it work more efficiently. It has also been used to lower blood pressure in dogs and cats.

Side Effects: This drug may cause your pet to become very tired. It may also slow the heartbeat too much if the dose is too high for your pet. Some dogs experience diarrhea while on this drug. If your pet has been on atenolol for a long time, you should not stop giving the drug suddenly or your pet may experience worse problems. 

Precautions: Animals with heart block or very slow heart rates may have problems taking this drug. Atenolol may also have some effects on the lungs. If your pet has asthma or other lung disease, please talk to your veterinarian before using this drug. 

Directions: Atenolol is usually given orally once or twice daily to dogs and once daily to cats.

Remember: Atenolol should be stored in a tight, light resistant, child proof container away from all children and other household pets. If your pharmacist has compounded a special formulation for you, please observe the noted expiration dates for the product.

If you miss a dose of this medication you should give it as soon as you remember it, but if it is within a few hours of the regularly scheduled dose, wait and give it at the regular time. Do not double a dose as this can be toxic to your pet.