Heartworm in Dogs: Lifespan, Hotspots, and Natural Remedies

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The Can Dogs Eat It Team

Heartworm in Dogs: Lifespan, Hotspots, and Natural Remedies
Reading Time: 8 minutes

joana garridoReviewed By Joana Garrido DVM

Heartworm in dogs is a covert blood-borne parasite present in all 50 states of the United States. It poses a severe risk to dogs when contracted and given enough time to reproduce.

Heartworm infestations can cause life-threatening health complications, such as multiple organ damage if not caught early.

We want to highlight the many dangers this parasite poses to canines as well as share vital information about its risk factors and natural remedies that can help get rid of minor heartworm infestations.

What Is Heartworm in Dogs?

Heartworm in dogs is a type of parasitic roundworm scientifically known as Dirofilaria immitis.

When fully grown, it resides in the heart and lungs of canines as well as nearby associated large blood vessels. In rare cases, this parasite can invade other parts of the circulatory system, which will be discussed later.

How Do Dogs Contract Heartworm?

Heartworm is contracted by dogs through mosquito bites. Mosquitoes are the intermediate hosts of the parasite. It means that the heartworm temporarily resides in the insect for a short period of time until it becomes infective.

Over 70 species of mosquitoes are capable of transmitting heartworms to dogs. In the USA, nearly 30 mosquito species can become hosts of the parasite according to a study.

What Is the Heartworm’s Life Cycle in Dogs?

a dog is having a checkup by the vetThe life cycle of heartworm in dogs has 3 stages and it goes as follows:

Stage 1

Adult female heartworms produce offspring called microfilariae in the bloodstream of dogs. When mosquitoes feed on an infected canine, they ingest the immature heartworms and become short-term hosts.

It will take around 10 to 14 days for the juvenile parasites to develop and grow into infective larvae inside the mosquito.

Stage 2

Infected mosquitoes pass off the heartworm larvae to dogs during feeding. The parasites enter the bite wound and into the bloodstream. After about 6 months, the infective larvae will mature into adult heartworms.

Stage 3

Full-grown male and female heartworms will mate to produce microfilariae, which are released into the bloodstream, waiting to infect another mosquito.

How Long Do Heartworm in Dogs Live?

Heartworm in dogs can live for a long time, approximately between 5 and 7 years. Within this period, the parasite has more than enough time to multiply, increasing the danger of severe infestation in infected dogs.

Worm burden is a term used to describe the number of worms in an animal. One dog can have a worm burden of up to 300.

The long lifespan of heartworm also gives it more chances of spreading to dogs and other animals such as cats, ferrets, foxes, coyotes, jackals, and wolves, especially during mosquito season.

What Areas in the United States Are Considered Heartworm Hotspots?

2022 US heartworm incidence mapAlthough heartworm in dogs is found in all 50 states in the country, some places have a higher prevalence of heartworm infestation than others.

According to the American Heartworm Society’s 2022 report, the lower Mississippi Delta has the highest cases of heartworm incidence.

States with the most diagnosed heartworm cases include:

  • Alabama
  • Arkansas
  • Louisiana
  • Mississippi
  • Texas

New heartworm hotspot areas were also observed, which are:

  • Tucson, Arizona
  • Connecticut
  • Boise, Idaho
  • Kansas
  • Massachusetts
  • Bismarck, North Dakota
  • Oregon
  • Seattle, Washington

Outside the United States, the Dirofilaria immitis heartworm is found in Australia, Europe, Japan, and other warmer countries.

What Health Complications May Arise from Heartworm Disease in Dogs?

An ill looking dog with HeartwormIf heartworm infestation in canines is not given timely treatment, it deals damage to the heart, lungs, and blood vessels of dogs. Some of the most common potentially fatal health complications that may arise are:

Arterial Inflammation and Scarring

As heartworm starts to grow and develop in the heart of dogs, they can cause damage to the artery lining. The dog’s body will respond by triggering inflammation in the artery to promote healing.

However, it is not enough to counteract the damage done by the parasite and instead contributes to wreaking havoc on the cardiovascular system.

Dog owners should also note that heartworms may release a bacterial organism called Wolbachia pipiens when they die. This microorganism is believed to exacerbate inflammation and increase the risk of shock.

Heartworm infestation that goes over 1 year will result in artery scarring and less flexible blood vessels.

Hindered Blood Flow

If the worm burden of an infected dog continues to increase, normal blood flow in the body will be compromised.

A large group of heartworms can block the blood vessels, forcing the blood to find other arteries where it can flow easily.

As a result, fluid accumulation may occur around the lung’s blood vessels. This keeps the organ from properly oxygenating the blood, which may lead to respiratory issues.

Heart Failure

Severe heartworm infestation can cause blockages in heart valves and even an entire heart chamber. Progression to this health complication may predispose infected dogs to cardiovascular collapse and heart failure.

Caval Syndrome

Caval syndrome is a severe form of heartworm disease in dogs. It occurs when the parasites migrate from the pulmonary artery to the vena cava, right atrium, and right ventricle of the heart due to overpopulation. It causes obstruction of blood into and through the right heart.

A study states that around 16% to 20% of dogs with heartworms may develop caval syndrome. It has a high mortality rate, ranging between 30% and 40%. The prognosis remains poor even after surgical removal of the heartworms.

What Are the Signs of Heartworm Disease in a Dog?

A border collie with HeartwormHeartworm disease has 4 stages of progression and each of them has the corresponding clinical signs:

Class 1: Mild heartworm diseaseMostly asymptomatic
Occasional dry cough
Class 2: Mild to moderate heartworm diseaseLethargy
Increased coughing
Weight loss
Class 3: Severe heartworm diseasePersistent cough
Exercise intolerance
Breathing difficulties
Right side heart failure
Class 3: Caval syndromeShock

Most cases of heartworm disease in dogs barely come with visible symptoms during its early stages. Thus, the health issue is often overlooked until it is too late.

For this reason, routine annual heartworm testing is strongly encouraged to check if your dog has become a carrier of the life-threatening parasite.

2 Natural Remedies for Heartworm in Dogs

Is your dog tested positive for minor heartworm infestation? Here are 3 home remedies you can try to help eliminate these pesky parasites.

1. Ginger

fresh ginger

In an in vitro study, ginger is found to exhibit the strongest microfilaricidal activity against Dirofilaria immitis when tested along with two other plants namely green chiretta and Tinospora crispa.

Its aqueous extract was able to significantly reduce the relative movability of the parasite to 0% by causing spastic paralysis within 3 hours post-treatment.

In a different research, infected dogs were subcutaneously injected with alcoholic extracts of ginger root. It was able to induce mass annihilation of immature heartworms in the bloodstream by 83% to 98%.


  1. Purchase organic ground ginger root. It can be found in the spice aisle in grocery stores or sold in online shops.
  2. Check the product before buying. Make sure it is made out of 100% ginger and does not contain other mixtures of spices.
  3. Mix 10 to 25 milligrams of ground ginger root for every pound of body weight into your dog’s food or water. Use it once a day.

Nutritional information

  • Ginger contains gingerol, which is a compound that helps improve blood circulation, lowers blood pressure, and reduces the risk of cardiovascular problems in canines.
  • Ginger provides several nutrients to dogs including niacin, riboflavin, calcium, and iron.


Ginger can interfere with blood clotting. Thus, it is not advised to use this herb on dogs with bleeding disorders or dogs prescribed with anticoagulant medications. In this case seek for veterinarian advice.

2. Neem

neem leaves

Results in a study show that the ethanolic leaf extract of the neem plant was effective in reducing the microfilariae circulating in infected dogs.

Around day 60, the plant was able to minimize the population of immature heartworms to 77.9% and 86.7% after administering a dose of 25 and 50 milligrams per 2 pounds of body weight twice a day, respectively.

On day 80, a 49.5% and 64.1% reduction were recorded. Researchers also noted that participating dogs did not show symptoms of toxicity during the entire experiment.


  • 1 cup water
  • 5 fresh neem leaves
  • 1 tablespoon raw honey


  1. In a small pot or saucepan, bring a cup of water to a boil.
  2. Add all fresh neem leaves to the boiling water and steep for 5 to 10 minutes.
  3. Mix honey with the liquid, then stir until well incorporated.
  4. Turn off the heat and allow the neem tea to cool down before serving it to your dog.
  5. For every 10 pounds of your dog’s body weight, offer your dog ⅓ teaspoon of neem leaf tea.
  6. Administer this home remedy for heartworm in dogs twice a day.

Nutritional information

  • Neem in its oil form acts as an insect repellent for dogs that wards off disease-carrying fleas and mosquitoes.
  • Neem oil has antibacterial and antifungal properties good for relieving skin problems in dogs such as scabies and ringworms.


It is not yet well-researched if neem has bad side effects on pregnant dogs. Just to be safe, avoid using it on expecting dams.

FAQs About Heartworm in Dogs

An ill looking corgi

1. What causes heartworms in dogs?

Heartworms in dogs are commonly caused by a parasitic roundworm called Dirofilaria immitis. Your dog can contract it through bites of mosquitoes infected with heartworm larvae.

2. How common is heartworm in dogs?

According to a 2020 study, the estimated prevalence of heartworm infection in dogs based on published papers around the world is 10.91%.

However, it should be noted that numerous dog owners fail to let their dogs take yearly heartworm tests. Thus, more cases of heartworm disease in dogs still remain undocumented.

3. What are the first signs of heartworms in dogs?

The very first sign of heartworms in dogs is mild coughs. This symptom is usually inconspicuous, making it easy to miss.

If you do catch your canine companion having coughs, get him checked by the veterinarian.

They will conduct a series of diagnostic tests such as chest X-rays, antigen tests and complete blood tests, which require blood samples to identify if your dog is positive for heartworms.

The earlier heartworm disease is diagnosed and treated, the less likely your dog’s life will be in danger.

4. At what age can dogs get heartworms?

Dogs at any age can get heartworms. However, these parasites are commonly seen in adult dogs rather than puppies since it can take 5 to 7 months to mature fully. Thus, 7-month-old puppies and older are advised to undergo heartworm testing.

5. Are heartworms in dogs contagious?

Heartworms in dogs are not contagious. It cannot be transmitted from dog to dog and is only contracted through mosquito bites.

However, a high prevalence of infected dogs means more mosquitoes may become hosts of these parasites, further increasing the spread of heartworm disease and causing an outbreak.

6. How to prevent heartworm in dogs?

The best way to prevent heartworm in dogs is by giving them monthly heartworm-preventive medications.

Part of dog heartworm prevention is to apply dog-friendly mosquito repellent on your dog and consider attaching fly screens on every window, door, vent, and chimney in your home.

Prevent mosquitoes from breeding by removing or covering stagnant water in and around your property.


Heartworm in dogs is present all over the 50 states in the U.S.A. Infected canines need timely treatment or else the parasites will cause serious cardiovascular and respiratory damage.

Early and minor heartworm infestations in dogs can be ameliorated through natural remedies like ginger and neem leaves. However, if your dog’s condition is severe, only medical treatment will be able to eliminate this health issue.

Life-threatening health complications caused by heartworm disease can be easily prevented through regular yearly heartworm testing and monthly heartworm preventive administration.

Aside from heartworms, our four-legged friends are vulnerable to catching intestinal parasitic worms too. Find out how to get rid of them by reading our article “5 Natural Home Remedies for Worms in Dogs.