5 Heartworm Facts You Need To Know

Kate Barrington
by Kate Barrington
April is Heartworm Awareness Month, and we wanted to start it off with these interesting heartworm facts that all pet parents should know.

Heartworm is a serious disease that affects both dogs and cats. This disease is extremely dangerous and, if it is not treated properly, it is often fatal. You may already know the basics about this disease but the more you know, the better equipped you will be to prevent it or, in the worst case scenario, fight it. Here are just a few interesting heartworm facts that you may not know.

Related: A Pet Parent’s Guide To Heartworm Treatments

1. Heartworm can ONLY be transmitted by mosquitoes. When a mosquito bites a dog or cat that is already infected with heartworm, it picks up some of the baby worms – these microscopic worms are called microfilaria. Over a period of 10 to 14 days, then, the microfilaria develop into larvae – this is the infective stage of the disease. After this point, if the mosquito bites a dog or cat, it will transfer some of the infective larvae and the larvae will develop over the next six months into adult heartworms.

2. Different mosquitoes carry heartworm at different times of year. There are 22 species of mosquito in the United States that have been identified which can carry heartworm. These species of mosquito are active at different times of day and during different times of the year, so your dog is at risk for contracting heartworm all year round, not just during the spring and summer when mosquitos are most active.

Related: Naturally Safe Mosquito Repellent For Dogs

3. Your dog could test negative for heartworm but still carry the disease. It takes about six months after a heartworm-carrying mosquito bites your dog for the infective larvae to develop into adults. During that time, the larvae travel through your dog’s blood stream to the heart and lungs where they develop and mature – at this point they will also start reproducing which means that your dog could begin infecting other dogs.

4. There is only ONE approved treatment for heartworm in dogs and none for cats. The only approved treatment for heartworm is a drug called Immiticide. This drug is arsenic-based and it must be given via injection two or three times to kill adult heartworms living in the blood vessels of the infected dog. This treatment also requires extensive X-rays, blood work, and other tests to determine the severity of the infection. Treatments can cost anywhere between $300 and $1,000.

5. Treating heartworm is 15x MORE EXPENSIVE than preventing it. Heartworm prevention is as simple as giving your dog a monthly pill, but treatment can be much more difficult. Dogs should be tested for heartworm once a year and they must be tested before starting heartworm prevention pills. Puppies younger than seven months can be started on a heartworm pill without being tested but they should be tested six months later.

Having learned a little bit more about this disease from our heartworm facts list, you should now be able to appreciate how serious it is. Unfortunately, many dogs that are infected with heartworm fail to show clinical signs until the disease has progressed into a very serious state. To keep your dog healthy, make sure to have him tested once a year and keep up with your monthly heartworm preventive pills.

Kate Barrington
Kate Barrington

Kate Barrington is the loving owner of two cats (Bagel and Munchkin) and a noisy herd of guinea pigs. Having grown up with golden retrievers, Kate has a great deal of experience with dogs but labels herself a lover of all pets. Having received a Bachelor's degree in English, Kate has combined her love for pets and her passion for writing to create her own freelance writing business, specializing in the pet niche.

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