Overview of Theophylline for Dogs and Cats

Theophylline, also known as Theo-Dur®, belongs to the class of drugs known as smooth muscle relaxants, affecting the respiratory muscles in dogs and cats. These drugs are airway dilators, opening the bronchial tubes.

Theophylline is chemically similar to theobromine (found in chocolate) and caffeine. It is also related to the drug aminophylline and oxtriphylline. Each of these drugs is properly called a methylxanthine.

Methylxanthine drugs, such as theophylline, work by inhibiting enzymes (phosphodiesterases) inside of cells and promoting dilation of smooth muscle in bronchial tubes and blood vessels.

This results in widening of the tubes and can assist breathing in certain situations.

Theophylline is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.

This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.

Brand Names and Other Names of Theophylline

This drug is registered for use in humans only.

Human formulations: Theo-Dur® (Key Pharmaceuticals) and various generic brands are available. Some are considered “extended release” preparations, exhibiting a longer duration of effect.

Veterinary formulations: None

Uses of Theophylline for Dogs and Cats

Theophylline is used in situations that require dilation of the airways.

Theophylline has been used as an adjunct treatment in heart failure, asthma, bronchitis and chronic lung diseases.

Precautions and Side Effects

While generally safe and effective when prescribed by a veterinarian, theophylline can cause side effects in some animals.

Theophylline should not be used in animals with known hypersensitivity or allergy to the drug.

Theophylline should be used with caution in animals with severe heart disease, abnormal heart rhythms, kidney or liver impairment or high blood pressure.

Theophylline may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with theophylline. Such drugs include certain antibiotics, phenobarbital, propranolol, caffeine, acetaminophen and furosemide.

Theophylline has been shown to cause stomach irritation and nervous system stimulation. Anxiety and restlessness are common side effects of treatment in dogs.

Other potential adverse effects include nausea, vomiting, and diarrhea.

Seizures can occur if the animal receives a significant overdose.

How Theophylline Is Supplied

Theophylline is available in a variety of milligram tablets ranging from 50 mg to 600 mg.

It is also available as a 80 mg/15 ml or 150 mg/15 ml syrup.

Dosing Information of Theophylline for Dogs and Cats

Medication should never be administered without first consulting your veterinarian.

For dogs, theophylline is dosed at 3 to 5 mg per pound (6 to 10 mg/kg) three times daily; higher doses may be prescribed with the twice-daily extended action preparations.

For cats, theophylline is dosed at 2 mg per pound (4 mg/kg) one to three times daily.

The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.