Theophylline: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Theo-Dur, Deriphyllin

Species with doses

Dogs, Cats, Horses and Ferrets

General dose range

4–19 mg/kg PO q12–24h (sustained-release) — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Chronic bronchitis (canine)
• Feline asthma / lower-airway disease (adjunct)
• Bronchospasm with reversible airway disease

Theophylline dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Bronchodilation (sustained-release): Papich 5e and Plumb’s p.72 (Bach 2004): extended-release 10 mg/kg PO q12h, increasing to 15 mg/kg q12h if no adverse effects and inadequate response. Narrow therapeutic index — dose on lean weight; fluoroquinolones and other CYP inhibitors raise levels.
• Immediate-release theophylline: Papich 5e: immediate-release theophylline 9 mg/kg q8h PO.

Cats

• Asthma / bronchitis (sustained-release): Papich 5e: sustained-release tablets 20 mg/kg (100 mg per cat) q24h, or ER capsules 25 mg/kg (125 mg per cat) q24h PO; interval may be extended to q48h long-term. Plumb’s p.72 (Johnson 2000): 20–25 mg/kg PO once daily in the evening. Evening dosing gives best absorption in cats.
• Immediate-release theophylline: Papich 5e: immediate-release theophylline 4 mg/kg q8–12h PO. (For aminophylline doses see the Aminophylline entry — aminophylline is about 80% theophylline.)

Horses

• Equine asthma (RAO): Papich 5e: theophylline 5 mg/kg q12h PO; aminophylline 12 mg/kg initially then 5 mg/kg q12h. Plumb’s p.72: aminophylline 5–10 mg/kg PO or IV twice daily (Lavoie 2003). IV use causes transient excitement — dilute and give slowly (≤25 mg/min). ARCI Class 3.

Ferrets

• Bronchodilation: Plumb’s p.72 (Williams 2000): 4.25 mg/kg PO two to three times daily.

Contraindications

Tachyarrhythmia, seizure disorders, significant cardiac disease. Many interactions (fluoroquinolones, cimetidine, fluvoxamine raise levels). Reduce dose in hepatic / cardiac failure and in the elderly.

Adverse effects

• GI upset, vomiting
• CNS stimulation — restlessness, hyperexcitability, tremor
• Tachycardia, arrhythmia; seizures with toxicity

Drug interactions

• Fluoroquinolones (enrofloxacin, ciprofloxacin), cimetidine, fluvoxamine, macrolides: inhibit metabolism → raised levels / toxicity — reduce dose
• Phenobarbital / rifampin: induce metabolism → lower levels
• Beta-agonists (terbutaline): additive cardiac and hypokalaemic effects
• Halothane: increased arrhythmia risk

Pregnancy and lactation

Crosses the placenta and enters milk; use in pregnancy only if benefit outweighs risk.

Monitoring

• Heart rate / rhythm and CNS / GI signs of toxicity
• Serum theophylline level where available (target ~5–20 µg/mL)
• Review co-medications that alter its metabolism

Toxicity and overdose

Narrow therapeutic index — toxicity causes vomiting, tachyarrhythmia, hyperexcitability, tremor, hypokalaemia and seizures, sometimes before milder warning signs.

Management: Stop the drug; control seizures (diazepam), manage tachyarrhythmia (beta-blocker / lidocaine), correct hypokalaemia and give IV fluids; multi-dose activated charcoal enhances elimination. Monitor ECG and potassium.

Clinical pearls

• A bronchodilator adjunct, not a substitute for the corticosteroid that treats the underlying airway inflammation
• Do not interchange immediate- and sustained-release products milligram-for-milligram — the kinetics differ
• Watch for additive toxicity when starting a fluoroquinolone or cimetidine — they raise theophylline levels

Mechanism of action

Methylxanthine. Non-selectively inhibits phosphodiesterase (raising intracellular cyclic AMP) and antagonises adenosine receptors, producing bronchial smooth-muscle relaxation, improved diaphragmatic contractility, mild diuresis, and CNS / cardiac stimulation.

Formulations and products

• Theophylline sustained-release 100 mg tablet
• Theophylline sustained-release 200 mg tablet
• Deriphyllin — Etofylline 84.7 mg + theophylline 25.3 mg, Tablet / injection (combination) (human-label)
• Theophylline SR (generic) — 100 / 200 / 300 mg, Sustained-release tablet (human-label)

Storage

Store at 15–30 °C, dry; keep sustained-release tablets intact.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other hormones, emergency drugs, supplements and other drugs

• Sertraline
• Sodium Bicarbonate
• Succimer (DMSA)
• Terbutaline
• Thiamine (Vitamin B1)
• Toceranib
• Toldimfos sodium (Organic Phosphorus)
• Tranexamic Acid

Frequently asked questions