Just one dose of ProHeart 12 provides protection for your dog all year long.

It can be tough to remember monthly medications for your dog, and heartworm disease is a year-round threat.

Ask your vet about the benefits of adding ProHeart 12 to your annual wellness visit. With no monthly doses to remember, there are no gaps in protection for a full year.

With ProHeart 12, heartworm disease protection doesn't have to be a hassle.

What Pet Parents and Vets are Saying

Year-round protection has a lot of benefits. Hear what pet parents have to say about what ProHeart does for their dogs, their families, and their peace of mind.

How Do Dogs Get Infected With Heartworms?

The short answer: mosquitoes. A single bite from an infected mosquito can put your dog at risk for developing heartworm disease.

  1. An infected mosquito bites your dog, infecting it with heartworm larvae.
  2. The heartworms then mature inside your dog, living in major vessels around the heart and even sometimes inside the heart itself.
  3. It could take longer than 7 months for the heartworms to be detectable with routine testing. An adult heartworm can grow up to a foot in length, living inside your dog’s heart and lungs.1

ProHeart 12 Is Effective & Safe

In three well-controlled studies, ProHeart 12:2

  • Was 100% effective against heartworm disease* in dogs

  • Was demonstrated to be safe for most types of dogs over 12 months, including:

    • Dogs pregnant or nursing

    • Collies sensitive to ivermectin—a common ingredient in monthly heartworm products

  • Had a similar adverse event profile to Heartgard® Plus

*Caused by Dirofilaria immitis.
Heartgard is a registered trademark of Boehringer Ingelheim.

2 x per year

ProHeart 6® (Moxidectin): Another Reliable Option

ProHeart 6 is a twice-yearly dose to prevent heartworm disease in dogs

  • 20 million doses sold over a 10‑year period3

  • Demonstrated safe in special populations like:4

    • Dogs pregnant or nursing

    • Dogs sensitive to ivermectin—a common ingredient in monthly products for heartworm disease

  • Many common medicines were given at the same time in clinical trials

Please see full Prescribing Information for ProHeart 6.

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Frequently Asked Questions

IMPORTANT SAFETY INFORMATION: See Prescribing Information for ProHeart 6 and ProHeart 12. Use ProHeart 6 in dogs 6 months of age or older and ProHeart 12 in dogs 12 months of age or older. Do not administer to dogs that are sick, debilitated, underweight, have a history of weight loss, or to those previously found to be hypersensitive to the drug. Hypersensitivity reactions may occur in some dogs when ProHeart is administered alone or with vaccines. Anaphylactic and anaphylactoid reactions can result in death and should be treated immediately with the same measures used to treat hypersensitivity reactions to vaccines and other injectable products. Reported side effects in clinical trials included vomiting, lethargy, diarrhea, anorexia, and hypersensitivity reactions. People should avoid inhalation, contact with eyes, or accidental self-injection. Certification is required before veterinarians and staff administer these products.

*From an infected mosquito. Caused by Dirofilaria immitis.


  1. AHS Canine Guidelines 2020. https://d3ft8sckhnqim2.cloudfront.net/images/pdf/2020_AHS_Canine_Guidelines.pdf?1580934824, accessed 1/27/21.

  2. McTier, T.L., Kryda, K., Wachowski, M. et al. ProHeart® 12, a moxidectin extended-release injectable formulation for prevention of heartworm (Dirofilaria immitis) disease in dogs in the USA for 12 months. Parasites Vectors 12, 369 (2019).

  3. ProHeart 6 Pharmacovigilance Data. Data on file. Zoetis. Inc.

  4. ProHeart 6 Freedom of Information Summary: 2001/06/06 Original NADA 141-189