Protect Your Dog: Practical Tips to Prevent Heartworms

Prevent Heartworms in Dogs  by Dr. David Price, Entomologist Updated January 19, 2026

Heartworm disease is a serious and preventable condition that affects dogs in all 50 U.S. states. Because treatment can be difficult and costly, veterinarians and the American Heartworm Society emphasize prevention as the safest and most effective approach.

This guide focuses specifically on how to prevent heartworms in dogs, from routine veterinary care and preventative medications to simple environmental steps that reduce mosquito exposure. These practical strategies help protect your dog long before heartworms become a medical emergency.

If you would like a detailed explanation of how heartworm disease develops, including symptoms, testing, and treatment options, see our Heartworm Disease in Small Dogs reference guide.

Heartworm prevention is critical because heartworm disease can cause severe, sometimes irreversible damage in dogs.

Understanding how heartworms are transmitted makes it easier to see why prevention is so critical to protecting your dog’s long-term health.

What Are Heartworms?

Heartworms are parasitic worms transmitted to dogs through the bite of an infected mosquito. Once inside a dog’s body, the parasites develop within the bloodstream and eventually settle in the heart and lungs if left unchecked.

Dogs are the primary hosts for heartworms, which means the parasites can mature and reproduce in their bodies. Other animals may be affected, but dogs face the greatest risk of long-term health complications when infected.

From a prevention standpoint, the most important thing to understand is that heartworm disease does not spread directly from dog to dog. Mosquito exposure is the only way infection occurs, which is why consistent prevention and environmental control are so effective.

For a detailed explanation of how heartworms develop inside the body, including symptoms, testing, and treatment, visit our Heartworm Disease in Small Dogs guide.

How Are Heartworms Transmitted from One Animal to Another?

Heartworms cannot live outside a host. They live, breed, and grow primarily in the heart and pulmonary arteries of the animals they infect.

When a female heartworm produces baby worms called microfilariae, she releases them into the host animal’s bloodstream.

When a mosquito bites an infected dog, the mosquito ingests some of the microfilariae with the blood.

Once inside the mosquito, the microfilariae mature to the next stage as an infective larva. Heartworms must spend time in a mosquito’s digestive tract to become infective.

Heartworm disease cannot be passed to another animal in any other way, such as through licking, biting, or feces.

When the mosquito bites another dog or susceptible animal, the infective larva enters the new host’s bloodstream through the mosquito bite.

Heartworm Symptoms in Dogs

In the early stages, dogs infected with heartworms often show no obvious signs.

Because the parasites take several months to mature, heartworm disease can progress silently before symptoms appear.

As the infection advances, affected dogs may develop a persistent cough, reduced energy, difficulty breathing, or fatigue after normal activity. In severe cases, heart and lung function can become compromised.

Because early symptoms are subtle or absent, routine testing and year-round prevention are essential. A full discussion of symptoms and disease progression is covered in our Heartworm Disease in Small Dogs
guide.

• persistent cough
• pronounced fatique
• labored breathing
• swollen belly

5 Tips for Heartworm Prevention in Dogs

As nasty as heartworm disease is for our beloved friends, there is no vaccine, and the treatment itself is toxic to your pet. Heartworm prevention for dogs is by far the best approach.

Heartworm Prevention Medicine

A variety of heartworm prevention medications are available by prescription from your vet. There are chewable pills, topical applications, and injections available. Some are repeated monthly, and some last for six or 12 months.

The medication is formulated based on your dog’s weight, so the dosage may change as your dog grows.

According to the American Heartworm Society recommendations, your furry friend needs continual protection, starting at eight weeks of age.

Some heartworm prevention medication also effectively protects against fleas, ticks, tapeworms, and other parasites. Again, your vet can advise you on the best protection for your pup.

Routine Checkups

Only your veterinarian can prescribe heartworm prevention medications, so you must maintain regular checkups.

Your vet will also test for heartworms as part of your dog’s annual checkup because catching the disease early makes the treatment more effective. And regular health care keeps your pup healthy and happy.

Keep Your Yard and Home Mosquito-Free

Mosquitoes are essential to the spread of heartworms and heartworm disease. Without mosquitoes, your dog would never be at risk from these parasites! So, work to keep your yard mosquito-free by the following means:

• Keep your grass mown short.
• Dethatch the lawn.
• Avoid overwatering.
• Repair any leaking irrigation and faucets.
• Eliminate sources of standing water.
• Treat water features with a mosquito larvicide.
• Chlorinate swimming pools.
• Hire a professional pest control service.

The above yard care tips work to make your property less appealing to mosquitoes by denying them the habitat they seek. And an added benefit of professional mosquito control is that it can protect your dog and the rest of your family from other vector-borne diseases, like West Nile and Zika viruses.

Commit to Routine

Continual heartworm protection for dogs is essential to your furry friend’s health. Heartworm disease has been diagnosed in all 50 states in America.

Veterinarians, the American Heartworm Society, and the federal government urge dog owners to provide heartworm protection year-round.

So, commit to the annual vet exams to check for heartworms and to get the next set of preventative medication so that your best friend never faces a grueling struggle with heartworm disease.

Strengthen Your Dog’s Immune System

Undoubtedly, the healthiest dog on the block can get heartworm disease if an infected mosquito bites it. But providing your dog with a wholesome diet, regular health care, and plenty of exercise will boost their immune system.

A healthy immune system won’t prevent heartworm disease, but it will enable your dog better to fight off the effects of the heartworm infection until you can provide treatment.

Be the Friend Your Dog Deserves & Start Heartworm

Be the Friend Your Dog Deserves & Start Heartworm.

Life gets hectic, and sometimes our best intentions slide. It happens. But this one just can’t wait. Your best friend needs your support and protection just as much as you need their love and companionship.

If you haven’t already, initiate mosquito control and start heartworm protection for dogs today. Ensure all the sloppy kisses, belly rubs, and snuggles for all the tomorrows to come.

Prevent Heartworms in Dogs:  Author Bio

Dr. David Price is an Associate Certified Entomologist of over 12 years and working in the Pest Management industry for over 25 years. The Director of Technical Services for Mosquito Joe oversees all training development and technical support to over 170 Franchises in 38 states and Washington.

Prevent Heartworms in Dogs
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