Can Cats and Dogs Safely Take Propranolol?

The autonomic nervous system is divided into two main branches: the sympathetic nervous system (responsible for the "fight or flight" response) and the parasympathetic nervous system. Sympathetic activity is transmitted to tissues through unconscious (autonomous) nerve impulses and blood circulation.

Within cells, there are target sites known as receptors, which can be stimulated by chemical substances released by nerves or glands. In the sympathetic nervous system, the chemical neurotransmitter released by nerves is called norepinephrine, while the chemical substance released by the adrenal glands is called adrenaline. These substances bind to receptors known as αadrenergic and βadrenergic receptors.

The effects of stimulation by adrenergic receptors include: an increase in blood sugar levels, an increase in heart rate, enhanced cardiac contraction, and increased oxygen consumption, leading to elevated blood pressure. Additionally, stimulation of the receptors can also cause relaxation of the bronchial tree, leading to the opening of airways and dilation of some blood vessels.

Propranolol is a type of medication known as a receptor blocker. Other related drugs include: esmolol, atenolol, and metoprolol.

Receptor blockers have a particularly notable impact on the heart, although they can also affect other organs. Propranolol can lower heart rate, cardiac output, the amount of oxygen required by the heart muscle, and blood pressure.

Propranolol is a prescription medication that can only be obtained from a veterinarian or prescribed by one. Although it has not been approved by the Food and Drug Administration for use in animals, veterinarians are legally permitted to prescribe it as an additional medication.

The formula for propranolol is as follows:

This medication is registered for use only in humans.

Human formulations include Inderal® (Ayerst), Intensol® (Roxane), and various generic formulations.

There are currently no formulations available for veterinary use.

Propranolol's Uses in Cats and Dogs:

1. The primary use of βadrenergic blockers in animals is for treating (and sometimes preventing) arrhythmias. Commonly treated arrhythmias include atrial fibrillation and flutter.

2. Propranolol is also used to treat supraventricular tachycardia and ventricular premature complexes.

3. It can reduce cardiac output and lower blood pressure, which is beneficial for animals with hypertension.

4. Reducing heart rate and myocardial contractility is beneficial for some cats and dogs with hypertrophic cardiomyopathy, especially when excessive myocardial contraction blocks blood flow channels.

5. Propranolol can also be used to treat hyperthyroidism in cats.

Precautions and Side Effects:

1. Generally, propranolol prescribed by a veterinarian is safe and effective, but it can also cause side effects in some animals.

2. Propranolol should not be used in animals known to be allergic to the drug.

3. Propranolol can suppress myocardial function and heart rate, reducing cardiac output. This can be a problem for animals with congestive heart failure, requiring very careful dosing.

4. Propranolol may interact with other medications. Consult your veterinarian to determine if any other medications your pet is taking could interact with propranolol. These include: sedatives, cimetidine, insulin, lidocaine, and theophylline.

5. Propranolol may cause some animals to become weak due to a slower heart rate or low blood pressure. However, pets rarely faint.

Dosage and Administration Information:

Before administering, always consult with a veterinarian.

Typical dosage for dogs is: three times daily, 0.15 to 0.5 mg per pound of body weight (0.3 to 1.0 mg/kg).

Typical dosage for cats is: 2.5 to 5 mg per cat, twice to three times daily.

Propranolol is often prescribed in combination with other medications, especially for pets receiving treatment for heart failure or arrhythmias. In these cases, lower initial doses may be prescribed.

The duration of treatment depends on the condition being treated and the pet's response to the medication. Even if your pet seems to have recovered, it is important to complete the full course of treatment unless the veterinarian provides specific instructions.