Dog Heart Medication: Pimobendan (Vetmedin), Furosemide and More

What Is Pimobendan (Vetmedin)?

Pimobendan is an "inodilator": it makes the heart muscle contract more strongly by making it more sensitive to calcium, and it widens blood vessels so the heart pumps against less resistance.^16,2,17 It was first approved in the US in 2007 for heart failure caused by mitral valve disease or dilated cardiomyopathy (DCM).^3,2 It's available as chewable tablets, an FDA-approved liquid and, since 2024, an FDA-approved generic.^3,15

Pimobendan isn't used in dogs whose heart problem is an outflow blockage, such as aortic stenosis, or in hypertrophic cardiomyopathy, where pushing the heart harder isn't helpful.^2,18

When Do Dogs Start Pimobendan?

• Mitral valve disease with an enlarged heart but no symptoms (ACVIM Stage B2): pimobendan is recommended to delay heart failure.^1,11 It isn't recommended for dogs with a murmur but no significant enlargement (Stage B1).^1,2 See enlarged heart in dogs.
• Heart failure (Stage C and D): pimobendan is a standard part of treatment, alongside other drugs.¹
• Dobermans with early DCM: pimobendan started before symptoms delayed heart failure or sudden death from a median of 441 to 718 days in the PROTECT trial.¹⁹

That's why your vet may recommend X-rays or an echocardiogram when a murmur is found: they show whether the heart is enlarged enough to start treatment.¹ See heart murmurs in dogs.

Pimobendan Side Effects

Most dogs tolerate pimobendan well.^2,20 Reported side effects include:^2,20,18

• Poor appetite, vomiting or diarrhea
• Tiredness

Less commonly, a faster heart rate or abnormal rhythms have been reported.²

Many problems seen in dogs taking it, such as coughing or breathing trouble, are signs of the heart disease itself rather than the drug, so report any change to your vet.² Kidney values often change in heart failure, mostly because of diuretics and ACE inhibitors; pimobendan's label also lists raised kidney values among reported effects, so your vet will check bloodwork.^2,9,7

Giving Pimobendan

• Timing: it's usually split into two doses about 12 hours apart.²
• Food: labels in Canada and the UK advise giving it about an hour before a meal. US labels don't specify, so follow your vet's instructions.^18,2,20
• Missed dose: give it when you remember unless the next dose is soon. Never give two doses at once.²⁰
• Keep chewables out of reach: they're flavored, so dogs may seek them out. If your dog eats extra tablets, call your vet or a pet poison line right away.^20,2
• Don't stop it suddenly or change the dose without talking to your vet.

Generic, Liquid and Compounded Pimobendan

The FDA approved the first generic pimobendan for heart failure in 2024. It has the same active ingredient, strength and form as Vetmedin.³ An FDA-approved liquid (Vetmedin Solution) is also available.¹⁵

Compounded pimobendan, made by a pharmacy rather than an approved manufacturer, is different. The FDA says its absorption is unknown and may be inadequate or variable, and that unapproved pimobendan shouldn't be imported from other countries.¹⁵ Ask your vet before switching to a compounded or imported product to save money.

Other Dog Heart Medications

• Furosemide (Lasix): the most common first-line diuretic. It removes fluid from the lungs and can be lifesaving in a heart failure crisis. Expect more drinking and urination; don't restrict water.^16,4,7
• Torsemide: a stronger diuretic, about 10 to 20 times as potent as furosemide, sometimes used when furosemide stops working well. In 2024 the FDA conditionally approved a torsemide product for dogs (UpCard-CA1).^16,21,1
• ACE inhibitors (enalapril, benazepril): relax blood vessels and reduce the strain on the heart. They can raise potassium and affect the kidneys, so blood tests are needed.^4,9
• Spironolactone: blocks the hormone aldosterone and is often added in heart failure. It's a potassium-sparing diuretic, so potassium and kidney values are monitored.^16,1,22
• Rhythm drugs: diltiazem and digoxin slow a fast heart rate, for example in atrial fibrillation; digoxin has a narrow safety margin and needs blood-level checks. Sotalol is often used in Boxers with ventricular arrhythmias.^16,23,8
• Sildenafil: treats high blood pressure in the lungs (pulmonary hypertension) in advanced disease.^16,24,1

Don't give your dog human heart medicines, over-the-counter supplements or "natural diuretics" in place of prescribed treatment, and tell your vet about every product your dog takes. Pain relievers such as NSAIDs can interact with ACE inhibitors and diuretics.⁹

Monitoring a Dog on Heart Medication

• Blood tests: kidney values and electrolytes are usually checked 1 to 2 weeks after starting or changing a diuretic or ACE inhibitor, then every few months.^9,22,7
• Sleeping breathing rate: count it at home. A rate consistently above 30 a minute can mean fluid is building up and medication needs adjusting.^6,25,1
• Rechecks: X-rays or an echocardiogram show how the heart is responding.¹

See congestive heart failure in dogs and heart disease in dogs.

Frequently Asked Questions

What does pimobendan do for dogs?

It makes the heart pump more strongly and widens blood vessels. It delays heart failure in dogs with valve disease and an enlarged heart, and helps dogs already in heart failure live longer.

What are the side effects of pimobendan in dogs?

Usually mild: poor appetite, vomiting, diarrhea or tiredness. Less often, a faster heart rate or abnormal rhythm. In the early-treatment trial, side effects were similar to placebo.

Should pimobendan be given on an empty stomach?

Labels outside the US advise giving it about an hour before a meal. US labels don't specify, so follow your vet's instructions and be consistent.

How long can a dog live on pimobendan?

It depends on the stage. Dogs that start before symptoms often live years, while dogs that start in heart failure typically live months to a year or more.

What happens if I stop giving my dog pimobendan?

Stopping it can let heart failure develop sooner or come back. Never stop heart medication without talking to your vet.

Is generic pimobendan as good as Vetmedin?

FDA-approved generic pimobendan has the same active ingredient, strength and form. Compounded versions aren't FDA-approved, and their absorption may be unreliable.

Is pimobendan hard on a dog's kidneys?

Kidney changes in dogs with heart disease are mostly linked to diuretics and ACE inhibitors, but raised kidney values have been reported with pimobendan too, so regular bloodwork is important.

What is the most common heart medication for dogs?

Pimobendan and furosemide are the most common, often combined with an ACE inhibitor such as enalapril or benazepril and spironolactone in heart failure.