Atenolol for Cats and Dogs

PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Atenolol Used for in Cats and Dogs?

Atenolol is a prescription heart medication used most often in cats and dogs to help treat abnormal heart rhythms that cause the heart to beat too quickly (tachycardia). Atenolol is also prescribed to help treat high blood pressure (hypertension) in dogs and cats.

It may also be prescribed to help treat hypertrophic cardiomyopathy (HCM) in cats, and in combination with other medications, to help treat hypertension caused by hyperthyroidism.

In dogs, atenolol can also be used to help treat certain abnormal heart beats called ventricular premature complexes (VPCs), arrhythmogenic right ventricular cardiomyopathy (Boxer cardiomyopathy), and certain obstructive heart diseases like pulmonic or aortic stenosis.

Atenolol is also used in ferrets to help treat a specific heart disease called left ventricular hypertrophy.

Atenolol is FDA-approved for human use under the brand name Tenormin® and the generic name atenolol. While Atenolol is currently not FDA-approved as a veterinary medication, it is readily utilized in the veterinary field, and veterinarians can legally prescribe certain human drugs in animals in certain circumstances. This is called extra-label or off-label use because this use isn’t described on the drug label. Your veterinarian will determine whether this medication is right for your pet.

In certain circumstances, your vet may recommend a compounded formulation of atenolol.

Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug, such as if your pet has trouble taking pills in capsule form, the dosage strength is not commercially available, or the pet is allergic to an ingredient in the FDA-approved medication.

Compounded medications are not FDA-approved. They’re created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs.

How Atenolol Works in Cats and Dogs

Atenolol is a beta-blocker, meaning it lowers the heart rate by blocking the beta-1 receptors of the heart from binding to naturally occurring chemical messengers in the body such as epinephrine (adrenaline) and norepinephrine.

This slows the heart rate, which helps the heart relax and pump more efficiently. Atenolol also lowers blood pressure, which helps relieve the workload on the heart.

Atenolol for Cats and Dogs Considerations

Atenolol should not be used in pets with certain medical conditions, such as congestive heart failure, slow heart rate (bradycardia), certain heart arrhythmias, or in pets who are hypersensitive to it.

Giving atenolol with certain medications can result in health risks to your pet, so it’s important to discuss your pet’s medications and medical conditions with your veterinarian.

It’s important to note that your pet needs to be monitored and closely supervised by your vet with follow-up visits and tests such as blood pressure measurement and ECG (electrocardiogram) to monitor their heart rate and rhythm while they are taking this medication.

Atenolol for Cats and Dogs Directions

• Follow the directions on the drug label or as provided by your veterinarian.

• If your pet has chronic kidney disease, your vet may recommend a reduced dosage. In higher doses, atenolol may mask symptoms of other conditions, such as hyperthyroidism or low blood sugar (hypoglycemia). It can also affect sugar levels, causing either high (hyperglycemia) or low (hypoglycemia) blood sugar. For this reason, it should be used with caution in pets with fragile diabetes.

• This medication is often given for long periods of time, so do not stop administering atenolol to your pet without talking to your veterinarian.

Missed a Dose?

Speak with your veterinarian about what to do if you forget to give a dose of atenolol. Generally, they may instruct you to give it when you remember, or if it is almost time for your pet’s next dose, to skip the missed dose and resume your normal dosing schedule.

Do not give extra or double doses.

Possible Side Effects of Atenolol in Cats and Dogs

Most pets tolerate atenolol well. Side effects are mostly seen in older pets or those with worsening heart disease.

If you see any of the following symptoms, please notify your veterinarian as soon as possible.

• Slow heart rate (bradycardia)

• Loss of appetite

• Low blood pressure (hypotension)

• Abnormal heart rhythms (arrhythmias)

• Diarrhea

• Fainting

• Decreased energy levels (lethargy)

Human Side Effects

Atenolol is also a prescription medication for humans, frequently with dosages different from those prescribed for your pet by a veterinarian.

Due to possible side effects, humans should never use medicine dispensed for their pets, and pets should not be given any medicine dispensed for a human’s use.

If you accidentally ingest a pet medication, call your physician or the national Poison Control Center hotline at 800-222-1222.

Monitoring Your Pet

Your veterinarian may recommend routine testing and monitoring of your pet’s heart depending on your pet’s individual needs, other medications they may be on, and/or the issue that initially caused your pet to be placed on this medication.

When To Call Your Vet

Call your veterinarian if any of the following apply:

• Severe side effects are seen (see above)

• Your pet’s condition worsens or does not improve with treatment

• You see or suspect an overdose

• You have additional questions or concerns about the use of atenolol

Atenolol Overdose in Cats and Dogs Information

Signs of an atenolol overdose can be severe and may require hospitalization.

Symptoms to monitor in cats and dogs include:

• Very slow heart rate (bradycardia)

• Lethargy

• Low blood pressure (hypotension)

• Weakness

• Collapse

• Vomiting

It’s important to pay attention to the signs above to determine if there is an accidental overdose.

If you suspect an overdose, immediately contact your veterinarian or an animal poison control center. Consultation fees often apply.

• Pet Poison Helpline® 855-764-7661

• ASPCA® Animal Poison Control 888-426-4435

How To Store Atenolol for Cats and Dogs

Follow these tips when storing your pet’s atenolol:

• Always confirm storage requirements by reading the label.

• Atenolol tablets should be stored at controlled temperatures between 68–77 degrees F (20–25 degrees C).

• Keep the container tightly closed to protect from moisture and light.

• Compounded medications should be stored according to the compounding pharmacy’s label.

• Keep out of reach of children and pets.