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Heartworm

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Are Your Pets Protected?

Heartworm is a parasitic infection which can cause complications or even death to animals that become infected.

heartworm-life-cycle_American_Heartworm_Society

Image: American Heartworm Society

Canine (Dogs)
Feline (Cats)
Others

Dogs are the primary host for heartworm, which is why often the parasite is known as "dog heartworm" although the same species affects other animals as well.

Dog heartworm infection is more well understood, and has been recognized since the 17th century. The first cases to be found in the United States occurred in 1856.

There is an estimated 100,000 cases of canine heartworm infections every year.
The average number of worms found in a positive dog's heart is about 15, but many dog species can host up to 250 adult worms.
Dogs can receive treatment using adulticidal anti-parasitic drugs, or surgery.
The most recent American Heartworm Association Canine Guidelines have vector control basics.
- For mosquito bite prevention, permethrin-based products have been shown to be safe for dogs when used as directed for pets. Permethrin is not safe for cats.
According to Dr. Tom Nelson, DVM, studies suggest that heartworm positive dogs are more attractive to mosquitoes due to particles found in their breath that develop from infection.
- By attracting more mosquitoes, it's more likely the parasite can spread.

What happens with infection? (Image warning)

Heartworm

When an animal is infected with heartworms, the parasite travels in the bloodstream until it arrives to the heart. It implants into the heart and slowly grows and reproduces. Eggs can be found in the bloodstream, which is how many veterinarians diagnose the presence of infection.

If an animal is already infected, starting prevention will not eliminate any current adult worms.
If your pet was on heartworm prevention and missed a dose, be sure to check with your vet before re-starting prevention.

The worms can grow up to a foot long, and can restrict blood flow causing heart failure. While there is often a chance of survival, most cases are fatal.

Are humans susceptible to heartworm?

Human cases of heartworm are extremely rare. It was first seen in 1885, but there have only been an estimated 120 cases reported in humans ever. In addition, infections in humans rarely mature into adult worms. Parasites like heartworm have their preferred hosts, such as dogs, meaning they don't survive as well inside other animals or humans.

However, the same species that transmit heartworm to animals can also transmit other parasites and viruses that humans can contract. That's why it's important for both human and animal health to minimize mosquito breeding.

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Does Mosquito Management test for heartworm in mosquitoes?

While Mosquito Management does not test for the presence of heartworm in collected specimens, we do identify adult and larval mosquitoes to determine the presence of potential vector species which may also transmit other ailments to humans. Mosquito Management does test mosquito specimens for the presence of arboviruses such as West Nile. Treatments are determined based on the quantity of concerning species. Learn more about treatment methods here.

crushed_mosquitoes

How Is Heartworm Transmitted?

Heartworm is now found in all 50 states, but is most common in the southwest region.
Infection takes place if a mosquito has contracted the parasite from a previous host by taking a blood meal.
After an incubation period of about two weeks, the mosquito can pass on the parasite.
At least five genera of mosquito in Florida are potential vectors. However, the American Heartworm Society mainly attributes cases to Aedes, Mansonia, and Anopheles. Other species around the country are possible vectors as well.

Why Is Heartworm A Problem?

Heartworm is preventable, but if ignored can be deadly for our pets.
- While dogs thankfully have treatment options, there is no currently approved drug treatment for heartworm in cats or ferrets.
  - Cats and ferrets are not the typical host for heartworm. However, in rare cases that infection does occur, it is typically fatal due to the lack of treatment options. See the Feline Heartworm section below for more.
- As with any medication, no treatment can be 100% effective - but regular prevention significantly reduces the risk of contracting the parasite.
Heartworm can be difficult to detect.
- Pets often hide symptoms, but a few noticeable ones to watch for may be:
  - Cough, fatigue, weight loss, and decreased appetite
- Heartworms secrete a protein that can suppress your pet's immune system. This can mask symptoms.
Heartworms develop slowly, taking around seven months to fully develop, so the onset of symptoms may be gradual. The slow development of symptoms may cause a delay in treatment.

You can find a full list of heartworm prevention options by visiting the Preventatives page of the American Heartworm Society. Consult your options with a veterinary professional to find out which prevention choice suits you and your pets.

Prevent Heartworm At Home

Dump Water

The mosquitoes most known for spreading heartworm breed in natural and artificial containers like buckets, plants, gutters, bird baths, and pet dishes.

Wash pet dishes regularly for good hygiene and to remove any eggs or larvae.

Treat Natural Containers

Treat, replace, or fill in natural containers in your yard.

Water holding plants like bromeliads can be treated regularly with BTI.
Fill in tree holes with epiphytes (like air plants) or pack with sand.
Visit our Bromeliad page to see recommendations on alternative plants or contacts with master gardeners.

Keep Mosquitoes Out

Remember: mosquitoes will use any water they can find to breed, indoors or out! Use screens on windows and doors that are left open.

Check indoor water for mosquito breeding, such as in vases and pet dishes.