Veterinary drug · Drug monograph

Terbutaline: veterinary dose and monograph

Terbutaline is a veterinary drug. Selective β2-adrenergic agonist bronchodilator — relaxes bronchial smooth muscle for rapid relief of bronchospasm. Indications include acute bronchospasm / feline asthma crisis (SC rescue); chronic bronchitis / lower-airway disease (oral maintenance); symptomatic bradyarrhythmia (chronotropic support). This monograph lists 7 reference doses for dogs, cats, horses and ferrets, each with route, frequency and source.

At a glance

Drug class: Veterinary drug
Also known as: Brethine, Bricanyl
Species with doses: Dogs, Cats, Horses and Ferrets
General dose range: 0.01–0.1 mg/kg PO q8–12h (PO) / as needed (SC) — check the species tables for the indication
Routes: SC, PO, IV
Last reviewed: 1 October 2026

Indications

Acute bronchospasm / feline asthma crisis (SC rescue)
Chronic bronchitis / lower-airway disease (oral maintenance)
Symptomatic bradyarrhythmia (chronotropic support)

Terbutaline 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

Terbutaline doses for dogs
Indication	Dose	Route	Frequency	Duration
Acute bronchoconstriction (parenteral)	0.01 mg/kg	SC	as needed	—
Bronchodilation (oral)	0.625–5 mg/dog	PO	q8–12h (by body size)	—
Premature labour (tocolysis)	0.03 mg/kg	PO	q8h	—

Acute bronchoconstriction (parenteral): Plumb's (Ettinger & Kantrowitz 2005): 0.01 mg/kg IV, IM or SC. Papich 5th ed gives 3–5 mcg/kg (0.003–0.005 mg/kg) SQ as a single emergency dose, repeatable in 4–6 h — start at the lower Papich figure in a compromised patient and titrate.
Bronchodilation (oral): Dosed by body size, not per kg. Plumb’s p.1102: small dogs 0.625–1.25 mg, medium 1.25–2.5 mg, large 2.5–5 mg per dog PO q12h (Johnson 2000; Ettinger 2005). Papich 5e: 1.25–5 mg per dog q8h PO. Bradyarrhythmias: 0.2 mg/kg PO q8–12h (Rishniw & Thomas).
Premature labour (tocolysis): Plumb’s p.1102 (Davidson 2008): 0.03 mg/kg PO or SC q8h; stop 48 h before the calculated whelping date so normal labour can proceed.

Cats

Terbutaline doses for cats
Indication	Dose	Route	Frequency	Duration
Acute asthma crisis (rescue)	0.005–0.01 mg/kg	SC	once; may repeat — a key emergency bronchodilator	—
Chronic bronchitis (oral)	0.05–0.1 mg/kg	PO	q8–12h	—

Acute asthma crisis (rescue): Plumb’s p.1102: 0.01 mg/kg SC or IM for acute exacerbations at home — response (50% fall in respiratory rate/effort) in 15–30 min; a heart rate near 240 shows absorption (Padrid 2000); 0.01 mg/kg IV, SC or IM (Cohn 2007). Papich 5e: 5–10 µg/kg q4h SC or IM — most commonly 0.05 mg per cat (0.05 mL of 1 mg/mL) SC.
Chronic bronchitis (oral): Papich 5e: 0.1 mg/kg q8h PO, or 0.625 mg per cat (¼ of a 2.5 mg tablet) q12h. Plumb’s p.1102 (Noone 1999): 0.312–0.625 mg per cat PO two to three times daily, up to 1.25 mg in larger cats. (0.312–0.625 mg per cat ≈ 0.06–0.125 mg/kg for a 5 kg cat.)

Horses

Terbutaline doses for horses
Indication	Dose	Route	Frequency	Duration
Bronchodilation (RAO / equine asthma)	0.002–0.005 mg/kg	IV	q6–8h	—

Bronchodilation (RAO / equine asthma): Papich 5th ed: "Not absorbed orally. Use IV for treatment of chronic RAO: 2–5 mcg/kg q6–8h IV or as needed" (= 0.002–0.005 mg/kg). CORRECTION (2026-08-26 audit): this row previously specified 0.02–0.06 mg/kg PO — a route Papich states does not work in horses, at roughly 10× the IV dose. Inhaled beta-2 agonists (e.g. albuterol) or clenbuterol are usually preferred. Monitor for tremor/tachycardia.

Ferrets

Terbutaline doses for ferrets
Indication	Dose	Route	Frequency	Duration
Bronchodilation	2.5–5 mg/kg	PO	q12–24h	—

Bronchodilation: Carpenter's 6th ed (Ferret cardiopulmonary table): 2.5–5 mg/kg PO q12–24h (much higher mg/kg than dogs/cats).

Contraindications

Tachyarrhythmia, hypertrophic cardiomyopathy with obstruction, hyperthyroidism. Caution with other sympathomimetics and in diabetic / hypertensive patients.

Adverse effects

Tachycardia, tremor, restlessness
Hypokalaemia at high / repeated doses
Excitement / nervousness

Drug interactions

Beta-blockers: antagonise the bronchodilator effect
Other sympathomimetics / theophylline: additive tachycardia and hypokalaemia
Non-potassium-sparing diuretics: additive hypokalaemia
Inhalant anaesthetics (halothane): arrhythmia risk

Pregnancy and lactation

Relaxes uterine smooth muscle (a tocolytic) — avoid near term; otherwise use only if necessary.

Monitoring

Respiratory rate / effort (efficacy)
Heart rate / rhythm and tremor
Serum potassium with high or repeated dosing

Toxicity and overdose

Overdose causes marked tachycardia / tachyarrhythmia, tremor, agitation and hypokalaemia.

Management: Supportive — a cautious beta-blocker (e.g. propranolol) for severe tachyarrhythmia (weigh bronchospasm risk), correct hypokalaemia, IV fluids and ECG monitoring.

Clinical pearls

Keep injectable terbutaline in the feline-asthma crash kit — SC dosing buys you time in a cat in respiratory distress
A home SC dose taught to owners can rescue a known asthmatic cat before transport
Tremor and tachycardia are expected β2 effects; persistent tachyarrhythmia means back off the dose

Mechanism of action

Selective β2-adrenergic agonist. Stimulates β2 receptors on bronchial smooth muscle, raising cyclic AMP to cause bronchodilation; also produces β2-mediated vasodilation, skeletal-muscle tremor and an intracellular potassium shift, with mild β1-mediated positive chronotropy.

Formulations and products

Terbutaline 2.5 mg tablet
Terbutaline 5 mg tablet
Terbutaline 1 mg/mL injection
Bricanyl — 2.5 / 5 mg tablet; 0.5 mg/mL injection, Tablet / injection (human-label)

Storage

Store at 15–30 °C; protect the injectable from light.

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.

Frequently asked questions

What is the dose of Terbutaline for dogs?

Reference doses for Terbutaline in dogs: 0.01 mg/kg SC as needed (Acute bronchoconstriction (parenteral)); 0.625–5 mg/dog PO q8–12h (by body size) (Bronchodilation (oral)); 0.03 mg/kg PO q8h (Premature labour (tocolysis)). Confirm against the label and the patient before use.

What is the dose of Terbutaline for cats?

Reference doses for Terbutaline in cats: 0.005–0.01 mg/kg SC once; may repeat — a key emergency bronchodilator (Acute asthma crisis (rescue)); 0.05–0.1 mg/kg PO q8–12h (Chronic bronchitis (oral)). Confirm against the label and the patient before use.

What is the dose of Terbutaline for horses?

Reference doses for Terbutaline in horses: 0.002–0.005 mg/kg IV q6–8h (Bronchodilation (RAO / equine asthma)). Confirm against the label and the patient before use.

When should Terbutaline not be used?