Brand Name: Vetmedin

Available in 1.25 mg, 2.5 mg, 5.0 mg and 10 mg chewable tablets (U.S.).  Capsule forms are available in Canada and Europe.

Background

Pimobendan is the first drug of a class of heart medications called inodilators. This drug differs from other heart medications because it helps the heart pump more efficiently in two ways. First, it opens up the blood vessels that take blood from the heart so the heart doesn’t have to work as hard. Second, it increases the strength of the contraction of heart muscle.

Improvements in heart function while on pimobendan have been seen within one week of starting to take the medication, and some dogs continue to show improvement over several weeks. Many owners report an improvement in their pet’s quality of life and well-being. Dogs who show improvement on it will likely remain on pimobendan for the rest of their lives.

Clinical Efficacy

One study (QUEST) has shown that when used with other cardiac medications, pimobendan can be effective for dogs with congestive heart failure (CHF) related to degenerative mitral valve disease (MVD).  Studies examining the use of pimobendan in dogs with congestive heart failure (CHF) dilated cardiomyopathy (DCM) are less convincing.

Another study (PROTECT) has suggested that pimobendan can delay the onset of CHF and/or decrease sudden death in Doberman Pinschers with subclinical dilated cardiomyopathy.  Dobermans administered pimobendan before showing clinical signs had an average increase in the time to CHF of about one year.

The EPIC study examined the use of pimobendan in delaying onset of CHF in dogs with MVD. This study showed that dogs with pre-clinical MVD (a murmur, but no clinical signs of CHF) could benefit from pimobendan if their disease was sufficiently advanced, i.e., had evidence of moderate-to-marked cardiac enlargement on radiographs. Dogs could expect to remain free of clinical signs for about 200 to 300 days longer if they received pimobendan than if they received a placebo pill. Dogs with mild MVD (little or no cardiac enlargement and a small leak in the valve) don’t warrant supplementation because most of these dogs will never develop severe disease.

Some veterinary cardiologists have used pimobendan for cats with myocardial failure, particularly when the disease is not related to a taurine deficiency, but that is a fairly rare condition in cats. The drug appears to be safe in cats, but studies clearly demonstrating a benefit are lacking.

One retrospective study has suggested a benefit of pimobendan in cats with hypertrophic cardiomyopathy (HCM).  However, this study has substantial flaws, and the data need to be verified by prospective studies before routine use can be recommended.

Pimobendan is not licensed for use in cats.

Side Effects

Rarely, dogs taking pimobendan vomit. Call your veterinarian if your dog vomits on this drug.

Interactions With Other Drugs

There are no reported drug interactions with pimobendan. Theoretically, using multiple phosphodiesterase (PDE) inhibitors together, such as pimobendan and theophylline, could result in excessive PDE inhibition and adverse effects, such as tachycardia, hyperexcitability etc, although no data exist showing this to be the case.

Concerns And Cautions

Pimobendan should not be used in dogs with hypertrophic cardiomyopathy or aortic stenosis.

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