Pimobendan

Pimobendan is a cardiac inodilator combining positive inotropic and vasodilatory effects. It is an established treatment for canine congestive heart failure caused by myxomatous mitral valve disease or dilated cardiomyopathy. It also delays heart-failure onset in appropriately defined stage B2 mitral disease. Selected feline and preclinical cardiomyopathy applications are more specialized.

Group

Cardiac inodilator

Mechanism of Action

Pimobendan increases sensitivity of cardiac contractile proteins to calcium, improving force generation at a given intracellular calcium concentration. It also inhibits phosphodiesterase III, increasing cyclic AMP in vascular smooth muscle and promoting vasodilation. Improved contractility together with reduced vascular loading can increase forward cardiac output and reduce congestive pressure in responsive cardiac disease.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Heart failure	0.25–0.3 mg/kg	PO	Every 12 h
Heart failure	0.125 mg/kg	PO	Every 12 h	Lower alternative described when an ACE inhibitor is used.
Heart failure	0.25 mg/kg	PO	Every 12 h
Emergency heart failure adjunct	0.1–0.3 mg/kg	PO	Every 12 h
Refractory stage D heart failure	0.3 mg/kg	PO	Every 8 h	Non-consensus intensification described by some specialists.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Heart failure	1.25 mg/animal	PO	Every 12 h
Heart failure	0.1–0.3 mg/kg	PO	Every 12 h	Weight-based alternative reported alongside fixed feline dosing.
Myocardial failure	1.25–1.5 mg/animal	PO	Every 12 h

Indications

Treatment of congestive heart failure in dogs with clinical myxomatous mitral valve disease or dilated cardiomyopathy.
Delay of congestive heart-failure onset in dogs with stage B2 preclinical myxomatous mitral valve disease and documented cardiomegaly.
Specialist treatment of selected preclinical dilated cardiomyopathy, particularly supported Doberman cases.
Extra-label adjunctive treatment of selected feline heart failure or systolic dysfunction, with disease-specific selection and a smaller clinical evidence base.

Contraindications

Obstructive cardiomyopathy or fixed outflow obstruction
Arrhythmia-prone patients require caution.

Interactions

Other phosphodiesterase inhibitors may compound effects.

Adverse effects

Arrhythmias are possible, especially with severe underlying cardiac disease.

Toxicity

Overdose commonly produces tachycardia and may cause hypotension or arrhythmias. Monitor ECG and blood pressure and provide appropriate cardiovascular support.

Preparations

Preparation	Form	Strength	Route
Pimobendan chewable tablet 1.25 mg	Tablet	1.25 mg / tablet	PO
Pimobendan chewable tablet 2.5 mg	Tablet	2.5 mg / tablet	PO
Pimobendan chewable tablet 5 mg	Tablet	5 mg / tablet	PO

Monitoring and Administration

Assess disease stage and monitor rhythm. Consider other heart-failure therapy according to disease severity. Acidic dissolution properties matter; compounded products may not match proprietary absorption.

Label daily amount 0.5 mg/kg may be split into two not-necessarily-equal portions about 12 hours apart; mathematical equal halves are an alternative only when appropriate to the actual tablet.