Propranolol

Propranolol is a nonselective beta-adrenergic antagonist with class II antiarrhythmic activity. Its principal veterinary use is control of selected tachyarrhythmias and excessive adrenergic cardiac stimulation. It has also been used in selected hyperthyroid or other endocrine-associated cardiovascular conditions. Clinical experience is greater in dogs and cats than in many other species.

Group

Nonselective beta blocker

Mechanism of Action

Propranolol blocks beta1 and beta2 receptors, reducing catecholamine-driven increases in cardiac rate, contractility and conduction. Effects at sinoatrial and atrioventricular nodal tissue slow impulse generation and transmission and can reduce ventricular response to rapid atrial activity. Reduced beta1-mediated renin release also contributes to cardiovascular effects. The drug’s nonselective profile extends its receptor blockade beyond the heart.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Tachyarrhythmia	20–60 mcg/kg	IV		Administer over 5-10 minutes to effect.
Tachyarrhythmia	0.2–1 mg/kg	PO	Every 8 h
Tachyarrhythmia — Initial	0.1–0.2 mg/kg	PO	Every 8 h
Tachyarrhythmia higher maintenance	1.5 mg/kg	PO	Every 8 h	Upper titration amount; use only after response-based escalation.
Heart failure adjunct	0.1–0.2 mg/kg	PO	Every 8 h
Serotonin syndrome-associated tachycardia	0.02 mg/kg	IV		Slow injection; titrate cautiously.

Cats

Use / stage	Dose	Route	Schedule
Tachyarrhythmia	0.4–1.2 mg/kg	PO	Every 8 h
Tachyarrhythmia	2.5–5 mg/animal	PO	Every 8 h
Tachyarrhythmia oral alternative	2.5–10 mg/animal	PO	Every 8–12 h
Heart failure adjunct	2.5–10 mg/animal	PO	Every 8 h
Hypertension	2.5–5 mg/animal	PO	Every 8–12 h

Horses

Use / stage	Dose	Route	Schedule	Instructions
Tachyarrhythmia	0.1 mg/kg	IV	Every 6–8 h	Slow IV; repeat only if needed.
Escalating arrhythmia treatment	Reference only	IV		If 0.1 mg/kg is ineffective, the reported regimen describes 0.5 mg/kg and gradual escalation up to 2 mg/kg IV, titrated to response; not a single broad dose range.
Tachyarrhythmia	0.4–0.8 mg/kg	PO	Every 8 h
Ventricular tachycardia	0.05–0.16 mg/kg	IV
Ventricular tachycardia	0.03–0.15 mg/kg	IV
Ventricular tachycardia	0.3–0.7 mg/kg	PO	Every 8 h

Ferrets

Use / stage	Dose	Route	Schedule	Instructions
Hypertrophic cardiomyopathy	0.5–2 mg/kg	PO, SC	Every 12–24 h
Hypertrophic cardiomyopathy	0.2–2 mg/kg	PO	Every 8–12 h

Indications

Control of selected supraventricular tachyarrhythmias or adrenergically driven ventricular ectopy in veterinary patients.
Reduction of excessive heart rate and other cardiovascular manifestations of selected hyperthyroid states in dogs or cats.
Specialist control of selected catecholamine-associated tachycardia, including some pheochromocytoma cases within a complete endocrine and cardiovascular plan.
Historical adjunctive management of selected feline hypertrophic cardiomyopathy or systemic hypertension, with limited outcome evidence.

Contraindications

Bradycardia, low cardiac reserve or poor systolic function
Bronchoconstrictive disease and impaired hepatic perfusion require caution.

Interactions

Hepatic enzyme or blood-flow changes alter clearance; other cardiac depressants may compound effects.

Adverse effects

Cardiac depression, weakness, fatigue and bronchoconstriction.

Toxicity

Overdose may cause bradycardia, hypotension, AV block, bronchospasm, hypoglycemia and CNS depression. Monitor ECG, glucose, potassium and perfusion; severe cases may require specific cardiovascular rescue or pacing.

Preparations

Preparation	Form	Strength	Route
Propranolol 10 mg	Tablet	10 mg / tablet	PO
Propranolol 20 mg	Tablet	20 mg / tablet	PO
Propranolol 40 mg	Tablet	40 mg / tablet	PO
Propranolol 60 mg	Tablet	60 mg / tablet	PO
Propranolol 80 mg	Tablet	80 mg / tablet	PO
Provanol propranolol hydrochloride 10 mg tablet	Tablet	10 mg / tablet	PO
Provanol propranolol hydrochloride 20 mg tablet	Tablet	20 mg / tablet	PO
Provanol propranolol hydrochloride 40 mg tablet	Tablet	40 mg / tablet	PO
Provanol propranolol hydrochloride 60 mg tablet	Tablet	60 mg / tablet	PO
Provanol propranolol hydrochloride 80 mg tablet	Tablet	80 mg / tablet	PO

Monitoring and Administration

Titrate using pulse, rhythm and respiratory response. Hyperthyroid cats may need less drug because exposure can increase.

Oral suspensions may settle; shake before use. Acidic pH 2.8-4 favors stability.

Repeated IV small-animal protocol begins 0.02 mg/kg slowly; canine cumulative maximum 0.1 mg/kg. Feline reports conflict between four repeats and a 1 mg/kg cumulative ceiling. Do not turn cumulative limits into per-dose caps. Route is not specified for canine noise-phobia or feline 2 mg/kg/day hyperthyroid reports. Equine oral/IV six-day fixed-dose escalation schedules are calendar protocols, not generic dose ranges.