Theophylline 101: What to Know if Your Veterinarian Prescribes Theophylline for Your Dog or Cat

Theophylline is a drug often prescribed by veterinarians to help relax the muscles in a dog’s or cat’s lungs and chest so they can breathe easier. It is a member of the methylxanthine group of medications and is designated as a smooth muscle relaxant. It is commonly prescribed to treat a wide range of respiratory conditions, such as pulmonary edema, feline asthma, chronic obstructive pulmonary disease, chronic cough, and in rarer cases, some heart conditions.

Theophylline belongs to a group of drugs called xanthine bronchodilators and is a close relative to aminophylline and caffeine. Your veterinarian may prescribe it under the brand names Theo-24®, Theochron®, Elixophyllin®, or Theodur®. It is available in a number of forms, including oral capsules, tablets, oral suspension, and transdermal gel. It is very well-absorbed after oral administration.

Theophylline works by directly relaxing the smooth muscle of the bronchial airway and pulmonary blood vessels to:

• Increase the contraction strength of the diaphragm and airway muscles.
• Speed up the beat frequency of the hair-like cells (respiratory cilia) that help clear mucus from the respiratory tract.
• Relax and enlarge constricted airways for conditions like asthma.
• Stimulate the central nervous system to breathe.
• Increase the need to urinate.

Theophylline is used as a bronchodilator in both dogs and cats to treat bronchoconstriction and inflammation associated with chronic inflammatory lower airway disease and feline asthma.

Theophylline may be used with corticosteroids, which may permit a lowering of the dose of the steroids that may cause adverse side effects. Theophylline is also used to treat both dogs and cats with collapsing trachea, intrathoracic airway collapse, and pulmonary edema.

• The most common side effects are restlessness and caffeine-like “jitters.” Some veterinarians may start your pet on a lower dose and then increase it after the first week to help your pet adjust.
• Nausea, vomiting, and frequent urination (diuresis) may occur but are generally mild and should resolve over time.
• The less common and more serious side effects include cardiac stimulation (increased heart rate) and seizures.

• Theophylline should be used with additional caution in animals with severe cardiac, renal, or hepatic disease.
• It should also be used with additional caution in animals with seizure disorders, gastric ulcers, hyperthyroidism, hypertension, and severe hypoxia.
• Theophylline may take longer for newborn and geriatric pets to metabolize. They may need additional monitoring to prevent toxicity.
• Pets with pre-existing cardiac arrhythmias (abnormal heart rhythms) or congestive heart failure may need additional monitoring.
• It should not be used in cats with hypertrophic cardiomyopathy or glaucoma, in which beta2-receptor stimulation would be detrimental.
• It should only be used in pregnant or nursing animals when the possible benefits outweigh the risks.

• Quinolone antibiotics (enrofloxacin, ciprofloxacin, orbifloxacin) will increase blood levels of theophylline dramatically (potentially creating toxicity) and the side effects listed above may become a problem.
• Other medications which can increase the activity of theophylline include cimetidine (Tagamet), clindamycin, erythromycin, lincomycin, corticosteroids, allopurinol and thyroid hormone supplementation.
• The effect of theophylline may be reduced when using phenobarbital to control seizures, with ketoconazole, an antifungal medication, or with furosemide, a diuretic.
• Theophylline may decrease the effect of beta blockers (heart medicines) such as propranolol and may decrease the effects of benzodiazepine tranquilizers such as alprazolam or diazepam.

Veterinarians prescribe a specific dosage of theophylline based on the pet’s weight and condition. It is available in a number of forms including oral capsules, tablets, oral suspension, and transdermal gel. It is very well-absorbed after oral administration. Be sure to follow your veterinarian’s dosing instructions carefully.

When the appropriate dosage form is not available, it may be compounded by a specialty pharmacy. Wedgewood Pharmacy specializes in compounding and provides medication options that help ensure accurate dosing, especially for hard to medicate pets.

The dosage forms and strengths below are the most commonly prepared by Wedgewood.

View all Theophylline options

If you miss giving your pet a dose, give the next dose as soon as you remember or, if it is close to the next scheduled dose, return to the regular schedule. Do not double dose to catch up. If you are not sure what to do, call your veterinarian and follow their directions.

An overdose of theophylline can cause an increased heart rate and seizures, which can be life-threatening in certain pets and requires immediate veterinarian intervention. Contact your veterinarian immediately if you suspect an overdose.

If you suspect your pet or another animal has accidentally overdosed or has eaten this medication inadvertently, immediately contact your veterinarian or the A.S.P.C.A.’s Animal Poison Control Center at 888-426-4435.

Remember to take your prescription container with you when you take your pet for treatment. If you or someone else has ingested this medication, call the National Capital Poison Center at 800-222-1222.

Compounded medicines are prepared for the exact strength your veterinarian prescribes. The price of the medication will depend on the dosage and the medication form, with certain dosage forms and higher strengths generally being more expensive.

In addition, the cost of a medication will depend upon the price of the other active pharmaceutical ingredients and may increase the cost of the finished drug.

What Is an Alternative to Theophylline?

If your dog or cat is unable to tolerate theophylline, your veterinarian may recommend another bronchodilator, such as terbutaline. Sometimes, both of these medications are used together to combat severe asthma.

Does Theophylline Stop Coughing in Dogs and Cats?

Theophylline belongs to a group of medicines known as bronchodilators. Bronchodilators are medicines that relax the muscles in the bronchial tubes (air passages) of the lungs. They relieve coughing, wheezing, shortness of breath, and troubled breathing by increasing the flow of air through the bronchial tubes.

Does Theophylline Help Dogs and Cats with Collapsed Trachea?

Yes. In addition to relieving coughing, wheezing, and shortness of breath, theophylline is also used to treat both dogs and cats with collapsing trachea, intrathoracic airway collapse, and pulmonary edema.

Can Theophylline Cause Anxiety in Pets?

Theophylline has been shown to cause stomach irritation and nervous system stimulation. Anxiety and restlessness are common side effects of treatment in both dogs and cats. Other potential adverse effects include nausea, vomiting, and diarrhea. Seizures can occur if the animal receives a significant overdose.

Why Is Theophylline No Longer Used?

Theophylline has a very narrow therapeutic window, which means it negatively interacts with various other drugs. This has led to the limitation of its use, but it is still prescribed by veterinarians when the benefits outweigh the risk.

How Quickly Does Theophylline Work in Dogs and Cats?

Theophylline should take effect within 1 to 2 days, and you should see improvements in your pet's symptoms.

Why Is Theophylline Given to Pets at Night?

Long-acting theophylline preparations have long been associated with improvement in overnight lung function. That is because it promotes higher blood levels at night when the disease is worse and lower blood levels during the day when lung function is routinely better.

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