Best Heartworm Prevention for Dogs: All You Need to Know | Herepup
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​Best Heartworm Prevention for Dogs: All You Need to Know

We’ve all heard that we need to take steps to prevent our dogs from getting infected with heartworms, but many owners know little about why or how to do this effectively. Some owners even believe that keeping their pets inside will be enough to save them from heartworms, but that is not the case.

Heartworm disease can be a serious issue growing in your pet for years before you even realize the signs, so the best way to save your pet from harm to prevent an infection from ever happening. The best prevention comes in the form of oral and topical treatments.

How does a dog get heartworms?

best heartworm prevention for dogs

Image Credit: Lifelearn

Heartworm larvae are transmitted to dogs by mosquitoes. The larvae make their way into the bloodstream and body.

The larvae then grow into adult worms that can be up to a foot in length and live for more than five years. They will lodge themselves in the heart, lungs, and blood vessels and begin reproducing.

This can cause serious problems for your pet, and up to 250 adult worms could be in your pet’s system at any time. Here's the life cycle of heartworm in dogs.

What happens to a dog with heartworm disease?

Many dangerous things that can happen to an infected dog. If left unchecked, these symptoms could cause your pet to go into serious condition. If you think your pet is at risk of getting heartworm disease, make sure you keep an eye out for the following symptoms:

  • Mild to severe coughing
  • Loss of appetite
  • Weight loss despite regular eating habits
  • Fatigue
  • Loss of breath (gasping for air)

If you notice two or more of these symptoms and believe your dog to be at risk for heartworms, have your dog tested immediately.

Is there a cure for a dog with heartworm disease?

Yes, there are treatments available. Many dogs get infected with heartworm. The treatment involves injecting your dog with an arsenic-based medicine that will kill the adult worms.

Dogs must be hospitalized while undergoing this treatment as it can be pretty harsh on their system, and they will need at least two dosages of medicine to ensure the worms are all dead. The procedure has advanced greatly over the years, but it can still be very harmful to some pets. Even though heartworm disease is treatable, it’s always better to avoid heartworms altogether.

Do I need to protect my dog?

It used to be advised for people to give their dog the best heartworm preventative for dogs they can find only if they lived in at-risk areas. But there have been cases of heartworm in nearly every region, and tracking the heartworm season can be confusing or complicated.

To make sure your dog is not put at risk, the important thing to do is to consider what is the best for dogs like yours. Remember that infected mosquitoes carry the disease, and the mosquitoes could come into your region unexpectedly if the climate is different than usual.

My dog has already had heartworms. Can he get it again?

Yes. You should continue to use preventative measures to keep him from going through the ordeal again.


How do preventative medicines work?

Preventative medicines affect larvae that make it into your pet. The medicine kills larvae so they are not able to grow in the adult worms that would give your dog heartworm disease.

For preventative medicine to be effective, it needs to be administered within six weeks of your dog being bitten by a carrier mosquito. This is why it is recommended that you administer your dog with heartworm preventative medicine monthly.

What is the best heartworm prevention for dogs?

The most common types of heartworm prevention medications include ivermectin (Heartgard), milbemycin (Interceptor), and selamectin (Revolution). Each of these drugs and the variations of them available will kill heartworm, and some of them will also kill roundworm, hookworm, tapeworms, whipworms, and even fleas. If you want to get complete coverage with one medicine, look for one here that gives the most protection.

Are heartworm prevention medications safe for my dog to use?

For the most part, yes. The drugs are generally safe and verified to be safe to use on your dog. There are always, of course, exceptions. Ivermectin has caused problems like ataxia and depression in high dosages, but the low dose in heartworm medicine should not cause any problems. Milbemycin and ivermectin can both cause problems in Collies and related breeds that are more at risk of neurological problems.

Are there more natural ways to prevent heartworm disease?

There are a growing number of owners who worry that treating their pets monthly with oral and topical heartworm prevention medicine is not good for their pets and may contribute to drug-resistant kinds of heartworm developing.

Here, one holistic doctor gives her reason for believing so:

Some recommended seasonal tracking and regular DNA testing as the best method. Not every region has the same risk for dogs to get heartworm because the temperatures have to stay in a certain range for larvae to be able to grow into adult worms. These owners recommended only giving your dog preventative medicine during risk months, and to have your dog regularly tested for heartworm larvae.

This method is not 100% perfect, however, because larvae can live in your dog’s system even if they cannot grow due to low temperatures. The larvae can live there for years and mature at a later time if the temperatures go up. This means that you need to pay close attention to the temperature and remember to dose your dog if they are at risk.

Choose to Protect Your Dog

Your dog has no way to naturally keep itself from being infected by heartworms, so take the time to make sure your best friend is safe from this debilitating disease.

The best dog heartworm prevention  is to treat your dog monthly. Many medicines also fight against other parasites like hookworm and roundworm, so giving it year-round will benefit your dog’s overall health. There are many different medicines to choose from, so find the one that’s right for your budget and your dog today.

It’s up to you to help your dog stay safe from heartworms. Choose your preventative wisely, stay informed so that your dog will be heartworm-free and healthy for years to come.


Dr. Laura Harris is our resident dog health expert. She started to fact-check dog health-related information for HerePup during her internship and contributes since then. Her expertise is in dog nutrition, senior dog care, especially critical care medicine and internal medicine.

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