Pimobendan is a prescription cardiac medication marketed under the brand name Vetmedin (manufactured by Boehringer Ingelheim). It is classified as an inodilator, meaning it has both positive inotropic (strengthens heart contractions) and vasodilatory (relaxes blood vessels) properties. Pimobendan works through dual mechanisms: it inhibits phosphodiesterase III (PDE-III) to increase cyclic AMP levels, and it sensitizes cardiac myofilaments to calcium, enhancing contractility without significantly increasing myocardial oxygen demand. Pimobendan is FDA-approved for the management of congestive heart failure (CHF) in dogs caused by myxomatous mitral valve disease (MMVD) or dilated cardiomyopathy (DCM), and the landmark EPIC trial demonstrated that it also delays the onset of CHF in dogs with preclinical MMVD (stage B2).
What Is Pimobendan Used For?
Veterinarians prescribe pimobendan for:
- Congestive heart failure (CHF) due to myxomatous mitral valve disease (MMVD), typically as part of a multi-drug protocol with furosemide and an ACE inhibitor
- Congestive heart failure due to dilated cardiomyopathy (DCM)
- Preclinical MMVD (ACVIM Stage B2): The EPIC trial (Evaluation of Pimobendan in Cardiomegaly) demonstrated that pimobendan delayed the onset of CHF by a median of approximately 15 months in dogs with advanced preclinical MMVD and cardiac enlargement
- Other cardiac conditions at veterinary discretion, such as certain congenital heart diseases
Pimobendan is a cornerstone of canine heart failure management. Consult a veterinarian or veterinary cardiologist for proper cardiac diagnosis and staging before starting therapy.
Dosage
The FDA-approved dose of pimobendan is 0.23 to 0.3 mg/kg (0.1 to 0.14 mg/lb) orally twice daily, ideally given approximately one hour before meals. The total daily dose is 0.5 mg/kg divided into two doses.
| Dog’s Weight | Approximate Dose (0.25 mg/kg BID) | Common Tablet/Chew Size |
|---|---|---|
| 5 lbs (2.3 kg) | 0.575 mg twice daily | 1.25 mg (half tab) |
| 10 lbs (4.5 kg) | 1.125 mg twice daily | 1.25 mg |
| 20 lbs (9 kg) | 2.25 mg twice daily | 2.5 mg |
| 40 lbs (18 kg) | 4.5 mg twice daily | 5 mg |
| 60 lbs (27 kg) | 6.75 mg twice daily | 5 mg + 1.25 mg or vet-directed |
| 80 lbs (36 kg) | 9 mg twice daily | 10 mg |
Vetmedin is available as chewable tablets in 1.25 mg, 2.5 mg, 5 mg, and 10 mg strengths. Administer approximately one hour before feeding for optimal absorption, as food can reduce bioavailability. If using Vetmedin Chew (soft chew formulation), food timing restrictions may differ; follow your veterinarian’s instructions.
Side Effects
| Common Side Effects | Serious Side Effects (Contact Your Vet) |
|---|---|
| Decreased appetite (usually mild) | Worsening cough or difficulty breathing |
| Mild diarrhea | Collapse or fainting (syncope) |
| Lethargy | Rapid or irregular heartbeat (arrhythmia) |
| Sudden abdominal distension (ascites) | |
| Sudden death (rare; related to underlying disease) |
In clinical trials, pimobendan was generally well tolerated. Most side effects observed in CHF patients may also be related to the underlying heart disease itself. Regular veterinary check-ups, including echocardiography and thoracic radiographs as directed, are essential for monitoring progression.
Drug Interactions
- Calcium channel blockers (verapamil, diltiazem): May counteract pimobendan’s inotropic effects.
- Beta-blockers (atenolol, propranolol): May reduce the positive inotropic effect; use with caution and veterinary oversight.
- Other positive inotropes: Combination may increase risk of arrhythmias.
- Furosemide and ACE inhibitors (enalapril, benazepril): Commonly used together with pimobendan in CHF management under veterinary supervision.
Always inform your veterinarian of all medications your dog is receiving.
Contraindications
Pimobendan should not be used in:
- Dogs with hypertrophic cardiomyopathy (HCM)
- Dogs with aortic stenosis or other conditions where augmentation of cardiac output is inappropriate
- Dogs with known hypersensitivity to pimobendan
Use with caution in dogs with certain arrhythmias. Accurate cardiac diagnosis (echocardiography) is essential before starting pimobendan, as its use in the wrong conditions can be harmful.
Storage
- Store at controlled room temperature, 68-77 degrees F (20-25 degrees C).
- Protect from moisture.
- Keep in original packaging.
- Keep out of reach of children and pets.
Frequently Asked Questions
What is the EPIC trial? The EPIC trial (Evaluation of Pimobendan in Cardiomegaly) was a landmark, multicenter, randomized, double-blinded clinical study that demonstrated pimobendan delayed the onset of congestive heart failure by a median of approximately 15 months in dogs with preclinical MMVD and cardiac enlargement (ACVIM Stage B2). This trial changed the standard of care for dogs with advanced preclinical heart disease.
Why does pimobendan need to be given on an empty stomach? Food reduces the absorption of pimobendan. Giving it approximately one hour before meals ensures optimal blood levels and therapeutic effect. The newer Vetmedin Chew formulation may have different food timing recommendations; ask your veterinarian.
Can pimobendan cure heart disease? No. Pimobendan manages clinical signs and slows progression of heart failure, improving quality of life and survival time, but it does not reverse the underlying cardiac disease. Long-term veterinary monitoring is essential.
Is pimobendan safe for cats? Pimobendan is not FDA-approved for cats and is generally contraindicated in cats with hypertrophic cardiomyopathy, the most common feline heart disease. However, it may be used off-label in cats with dilated cardiomyopathy under specialist supervision.
How long can a dog live on pimobendan? Survival time varies widely depending on the type and stage of heart disease, response to treatment, and overall health. Many dogs with CHF managed on pimobendan plus standard therapy live months to over a year after CHF onset. Dogs started on pimobendan at the preclinical stage (B2) may have significantly extended time before developing CHF. Your veterinarian or cardiologist can provide a more individualized prognosis.
This content is for informational purposes only and is not a substitute for professional veterinary advice. Always consult your veterinarian before starting, changing, or stopping any medication for your dog.