How To Prevent Your Dog From Getting Heartworms

Protect his little heart 💖

heartworm prevention for dogs

The best way to keep your dog from dealing with heartworm disease is to prevent him from getting infected in the first place.

And prevention is as easy as a routine of monthly prescription medication and annual testing. Not to mention it’s way easier, cheaper and less involved than treating the disease if your dog were to ever get it.

We spoke with Dr. Zach Marteney, a veterinarian and medical director at Meadowlands Veterinary Hospital in New Jersey, to learn all about the best heartworm prevention for dogs.

How do dogs get heartworms?

In order to know how to prevent heartworm disease in dogs, it’s important to know how they get it in the first place.

Heartworm disease, which is a very serious, and even fatal, parasitic infection in your dog’s heart, can be spread by mosquitoes.

An infected mosquito will release heartworm larvae on your dog’s skin when it bites him, and the larvae enter your dog’s body through the wound.

The larvae will mature as they make their way through your pup’s system, and they’ll ultimately end up in his pulmonary artery, where they can cause all sorts of serious problems, like liver damage, kidney damage, blood clots and even heart failure.

What to know about heartworm prevention for dogs

When it comes to preventing your dog from getting heartworm, routine testing and regular medication are the most important things.

Heartworm medication for dogs

Preventative heartworm medication for dogs isn’t something you can just snag over the counter — you’ll have to chat with your vet first.

“All available preventatives require a prescription from your veterinarian,” Dr. Marteney told The Dodo.

These medications prevent heartworm by going after the parasites in your dog’s body while they’re still larvae, before they have the chance to cause any real harm.

“Heartworm prevention works by killing the larvae after they're introduced by the mosquito bite, but before they're able to migrate to the heart and mature into an adult infection,” Dr. Marteney said. “Monthly preventatives kill those larvae when it's administered, so it's very important that they're given on time on a regular schedule.”

When it comes to these medications, there are a bunch of oral monthly preventatives available.

Heartgard Plus is a chewable tablet designed to prevent heartworm in dogs, and it has some of the best ratings. It’s available for dogs up to 25 pounds, dogs 26 to 50 pounds and dogs 51 to 100 pounds.

Simparica Trio is a combination medication that targets heartworm, fleas and ticks. It’s available for dogs 2.8 to 5.5 pounds, dogs 5.6 to 11 pounds, dogs 11.1 to 22 pounds, dogs 22.1 to 44 pounds, dogs 44.1 to 88 pounds and dogs 88.1 to 132 pounds.

There’s also an injectable option that your vet can administer either once or twice a year.

“An injectable long-acting preventative called ProHeart can last for 6 or 12 months (depending on the version used),” Dr. Marteney said. “This version remains in the dog's system consistently and kills heartworm larvae as they're introduced to the dog via mosquito bites, and can be given at an annual visit when vaccines are updated.”

If you’re trying to decide between oral and injectable preventatives, you can really go either way.

“Neither is better or worse — they're just different,” Dr. Marteney said. “The injectable form is often more expensive, and there is a small risk of an allergic reaction from the injection — this is true of most injections, including vaccines. However, it removes the risk of forgetting a dose of preventative.”

Heartworm test for dogs

Bringing your dog in for routine heartworm testing is really important because it’ll tell you whether or not he has an active infection.

“A heartworm test should also be run annually,” Dr. Marteney said. “This should be done at their annual exam, at the same time their vaccines are updated.”

Your vet can diagnose heartworm disease by testing your pup’s blood.

“A heartworm test is a simple blood test,” Dr. Marteney said. “The test looks for ovarian antigen produced by female adult heartworms and is very sensitive. A positive test is often followed up with a microfilaria test — looking at a drop of blood under the microscope to see if there are worm larvae that can be seen swimming around in the blood sample.”

Heartworm treatment for dogs

If your dog gets diagnosed, he’ll need heartworm treatment to get rid of any nasty worms.

Heartworm treatment for your dog will include:

  • Blood work and other tests — to find out how serious the infection is
  • Taking heartworm prevention medication — to target younger worms in his system
  • A series of steroids and antihistamines — to prevent inflammation
  • Heartworm killer medication (aka melarsomine) — to kill adult heartworms
  • Hospitalization — to make sure your dog doesn’t have any complications after the melarsomine injections

Since heartworm prevention medication is actually part of your dog’s treatment, too, it can still help, even if you weren’t able to keep your dog from getting infected.

But preventing your dog from getting heartworm disease in the first place is always going to be the best form of treatment. So make sure you get your pup on that preventative medication ASAP.

We independently pick all the products we recommend because we love them and think you will too. If you buy a product from a link on our site, we may earn a commission.