Heartworm disease is serious, expensive to treat and almost completely preventable. Heartworm prevention for dogs is one of the most important parts of routine care. An online vet can answer your questions and help you stay on track, while your regular vet handles testing and prescriptions.
Heartworms are spread by mosquitoes. When an infected mosquito bites, it can pass larvae to your dog. Over months, the worms grow and live in the heart, lungs and blood vessels. Damage can be lasting, even after treatment. Cats can get heartworm too. See heartworm in cats.
Early on, many dogs show no signs. Later signs include:
That is why prevention and testing are so important.
The American Heartworm Society recommends year-round prevention for dogs. Mosquitoes can appear during warm spells, and a missed month leaves a gap in protection. Many preventives also protect against intestinal worms.
Your dog should be tested before starting prevention and usually once a year after. Giving some preventives to a dog who already has heartworms can cause a reaction. Testing requires a blood sample at your clinic.
Heartworm preventives require a prescription in the US. NYP TeleVet vets do not prescribe, so your regular vet will test your dog and provide it. Learn more in can online vets prescribe medication?
Our guide to heartworm, fleas and ticks covers all three parasites together.
Yes, but treatment is long, costly and hard on the dog. Prevention is much safer and easier.
Yes. Mosquitoes get indoors too, so vets usually recommend prevention for all dogs.
Talk to a licensed vet 24/7, even on holidays, by chat, voice call or video call. Your first month is free with code FREEMONTH, then US $9.99/month, at nyptelevet.com/. One membership covers up to 6 pets, and you can cancel anytime.
Our vets can’t prescribe medication, but they’ll tell you what’s likely needed and when an in-person visit is the next step.
⚠️ Disclaimer: NYP TeleVet is not a substitute for professional veterinary care. For emergencies (trouble breathing, seizures, severe bleeding, collapse), go to the nearest veterinary clinic immediately.
🚫 Currently not available in Hong Kong.
Not sure what to do next? Ask a vet now.
