Vetmedin® and Vetmedin®-CA1 for Dogs

Stephanie Howe, DVM
By Stephanie Howe, DVM. Reviewed by Molly Price, DVM on Feb. 20, 2024


In This Article


PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Vetmedin® / Vetmedin®-CA1 for Dogs?

Vetmedin® is an FDA-approved veterinary medication prescribed for dogs that have been diagnosed with mild, moderate or severe congestive heart failure caused by valvular insufficiency or dilated cardiomyopathy (DCM).

Several studies have shown that pimobendan (the active ingredient in Vetmedin®) can delay the onset of congestive heart failure in dogs with myxomatous mitral valve disease (MMVD) and DCM and have shown that dogs can also have a better quality of life while on this medication. Vetmedin® is typically used in combination with other medications commonly prescribed for pets with heart conditions.

If your dog has been diagnosed with Stage 2 MMVD, meaning your dog has a moderately loud heart murmur which can cause an abnormally enlarged heart (cardiomegaly), your veterinarian may prescribe Vetmedin®-CA1, which is conditionally approved by the FDA for dogs in this specific pre-clinical stage of heart disease to delay the onset and slow the progression of congestive heart failure.

A conditional approval means that the FDA has allowed the manufacturer to market this medication on a year-by-year basis until stronger evidence of the medication’s effectiveness is presented to the FDA within the first five years before a full approval can be granted.  

Vetmedin® and Vetmedin®-CA1 contain the same active ingredient, pimobendan, at the same dose in chewable tablet formulations, but they have two separate labels because they are used for different purposes.

Vetmedin® does not treat all types of heart disease. Speak to your veterinarian to see if Vetmedin® is appropriate for your pet.

In certain circumstances, your vet may recommend a compounded formulation of the active ingredient in Vetmedin®, pimobendan. Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug (such as Vetmedin® chewable tablets), such as if your pet has trouble taking pills in capsule form, the dosage strength is not commercially available, or the pet is allergic to an ingredient in the FDA-approved medication. 

Compounded medications are not FDA-approved. They are created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs. You can learn more about compounded medications here.

Vetmedin®/ Vetmedin®-CA1 Considerations

Vetmedin®/Vetmedin®-CA1 should not be used in dogs with certain heart conditions (aortic stenosis, hypertrophic cardiomyopathy) or in dogs who are allergic to the medication.

Vetmedin®/Vetmedin®-CA1 should be used with caution in dogs younger than six months of age, dogs with birth defects of the heart, dogs with diabetes mellitus or other serious internal diseases, and in breeding, pregnant, or nursing dogs, as safety studies had not been performed in these animals at the time of this publication.

Giving Vetmedin®/Vetmedin®-CA1 with certain medications can result in health risks to your pet, so it is important to discuss your pet’s medications, including vitamins and supplements, and medical conditions with your veterinarian.

How Vetmedin®/ Vetmedin®-CA1 Works in Dogs

Vetmedin® helps improve heart function in two ways. First, it causes vasodilation, which is when the muscles of the blood vessels relax. This allows your dog’s blood vessels to widen for blood to flow more easily. When veins widen, it reduces the backup of blood that causes abnormal fluid accumulation in the lungs and/or body. The widening of arteries reduces the resistance that the heart pumps against and improves blood flow to organs.

Vetmedin® also indirectly acts on the muscle fibers of the heart to improve its ability to contract effectively. This allows the heart to pump blood forward through the heart and increases the volume of blood moved out of the heart to the rest of the body.

Vetmedin®/ Vetmedin®-CA1 Directions for Dogs

Follow the directions on the drug label or as provided by your veterinarian. They will determine an appropriate dose based on your pet’s weight. This daily dosage is often split into two doses, usually given 12 hours apart. The morning dose may differ from the evening dose, so follow your veterinarian’s directions closely.

Vetmedin® is best absorbed on an empty stomach.

Vetmedin® is often given for long periods of time. Do not stop administering Vetmedin® to your pet without talking to your veterinarian.

Missed a Dose?

Speak with your veterinarian about what to do if you forget to give a dose of Vetmedin®. Generally, they may advise you to give the dose when you remember. However, if it is almost time for your pet’s next dose, your veterinarian may instruct you to skip the missed dose and resume your normal dosing schedule. In most cases, your veterinarian may instruct you to not give extra or double doses.

Possible Side Effects of Vetmedin®/ Vetmedin®-CA1 in Dogs

The most common side effects of Vetmedin® and Vetmedin®-CA1 include stomach upset (decreased appetite, vomiting, and diarrhea).

Other possible side effects may include:

  • Decreased energy (lethargy)

  • Cough (Vetmedin®-CA1)

  • Difficulty breathing

  • Elevated kidney levels

  • Weakness

  • Fainting or collapse

  • Lack of coordination

  • Localized pain, such as in the neck or legs (Vetmedin®-CA1)

Human Side Effects

This medication is not for use in humans in any capacity.

Due to possible side effects, humans should never use medicine dispensed for their pets and pets should not be given any medicine dispensed for a human’s use.

If you accidentally ingest a pet medication, seek immediate medical attention or call the national Poison Control Center hotline at 800-222-1222.


Your veterinarian may recommend routine testing depending on your pet’s individual needs, other medications they may be on, and/or the issue that initially caused your pet to be placed on this medication. Recommendations for monitoring may include monitoring of blood pressure; X-rays of the chest, an X-rays of the chest, an electrocardiogram (to monitor heart electrical activity), or an ultrasound of the heart (echocardiogram).

Call Your Vet If:

  • Severe side effects are seen (see above)

  • Your pet’s condition worsens or does not improve with treatment

  • You see or suspect an overdose

  • You have additional questions or concerns about the use of Vetmedin®

Vetmedin®/ Vetmedin®-CA1 Overdose Information in Dogs

Overdoses of Vetmedin® can have serious complications, including fast heart rate and blood pressure abnormalities. Large overdoses over a prolonged period of time may cause abnormal heart rhythms and structural changes to the heart. Emergency treatment is often necessary when an overdose occurs.

If you suspect an overdose, immediately seek emergency veterinary care or contact an animal poison control center. Consultation fees often apply.

Pet Poison Helpline  855-764-7661

ASPCA Animal Poison Control  888-426-4435

Vetmedin®/ Vetmedin®-CA1 Storage

Vetmedin® should be stored at controlled temperatures between 68–77 F and brief exposure to temperatures between 59–86 F are acceptable. Keep the container tightly closed in order to protect the medicine from moisture and light. Always confirm storage requirements by reviewing the label.

Compounded medications should be stored according to the compounding pharmacy’s label.

Keep out of reach of children and pets.

Vetmedin®/ Vetmedin®-CA1 FAQs

How long does it take for Vetmedin®/ Vetmedin®-CA1 (pimobendan) to work?

Vetmedin® starts to work inside your pet’s body within 1-2 hours of administration. However, the effects may not be visible that soon. One study showed that the signs of heart failure in dogs taking Vetmedin® improved significantly within seven days. Your veterinarian may prescribe additional medications to help reduce the signs of congestive heart failure.

How long can a dog live on Vetmedin®/ Vetmedin®-CA1 (pimobendan)?

In 2006, a study showed that dogs with acquired atrioventricular valvular disease treated with Vetmedin® lived about three times as long as those taking an alternative medication (benazepril, an ACE inhibitor). On average, the dogs treated with Vetmedin® lived for 13 months in this study. The dogs treated with benazepril lived for an average of four and a half months.

 No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content contained in this article is sourced from public sources or the manufacturer.



  1. Boswood A, Häggström J, Gordon SG, et al. Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study-A Randomized Clinical Trial. J Vet Intern Med. 2016;30(6):1765-1779.

  2. Summerfield NJ, Boswood A, O'Grady MR, et al. Efficacy of pimobendan in the prevention of congestive heart failure or sudden death in Doberman Pinschers with preclinical dilated cardiomyopathy (the PROTECT Study). J Vet Intern Med. 2012;26(6):1337-1349.

  3. Lombard CW, Jöns O, Bussadori CM. Clinical efficacy of pimobendan versus benazepril for the treatment of acquired atrioventricular valvular disease in dogs. J Am Anim Hosp Assoc. 2006;42(4):249-261.


Stephanie Howe, DVM


Stephanie Howe, DVM


Dr. Stephanie Howe graduated from the University of Florida College of Veterinary Medicine in 2011, after receiving a Bachelor of Science...

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