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10 Myths About Heartworms

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Busting Myths

By Valerie Trumps


Heartworm infection is preventable, both through common sense measures and preventive medication. But the biggest prevention factor is an informed pet parent. Before you ignore the danger by thinking your cat or dog is safe from these pesky parasites, check out the following common myths to get the honest truth.

Myth 1: Mosquito Season Occurs the Same Time Every Year

According to the American Heartworm Society’s latest survey of veterinarians, unseasonably mild winters combined with early springs bring the perfect conditions for an early start to mosquito season. With the unpredictability of the weather in recent years, no particular months or seasons are guaranteed to be mosquito-free.

Myth 2: Pets Aren’t at Risk During the Winter

Although mosquitoes, like other insects, tend to die off in very cold weather, warm periods with rain can occur during the winter — even in northern states. Also, mosquito seasons can vary depending on the area and according to how much water is present. Don’t take the risk; get your pet year-round protection.

Myth 3: Dry Places Don't Have a Heartworm Problem

Even in places like Arizona, where the weather is very dry, conditions such as irrigation cycles and scenic ponds can harbor mosquitoes. In fact, according to the American Heartworm Society, heartworms have been found in all 50 states.

The Midwest is also prone to monsoons in the summer, when hot temperatures combined with humidity from incessant rain can create conditions similar to the south. The mosquito season may be shorter, but they still can be found.

Myth 4: Cats Can’t Get Heartworms

While heartworms primarily infect dogs, infestation can also occur in cats. Outdoor cats are especially at risk, especially where mosquitoes are in swarms, but cats that stay inside can still get bitten by a heartworm-carrying mosquito that gets into your house.

Myth 5: Heartworm Disease is Rarely Fatal

Fact: Heartworm disease is a serious, life-threatening illness that mandates preventive measures and aggressive treatment. If left unchecked and untreated, heartworms can multiply to 50 or even 100 in severe infections, and can block blood flow and oxygen availability. Your pet cannot live without adequate blood supply and oxygen to breathe.

Myth 6: It's OK if My Pet Misses a Month of Heartworm Preventives

Actually, the American Heartworm Society says you should be concerned if your pet is on a monthly preventive cycle. They also advise that you consult a veterinarian and immediately start your dog back on heartworm preventive medication and retest in seven months. Why seven months? Heartworms must be approximately seven months old before the infection can be diagnosed.

Myth 7: Heartworms are Contagious

Fortunately, this is untrue. The only way your pet can get heartworms is if he is bitten by an infected mosquito. Although that same mosquito can go on to bite another pet, it couldn’t transmit the heartworm from one animal to another. The incubation period of the heartworm in the mosquito makes it a one-bite deal.

Myth 8: People Can Get Heartworms from their Pets

Again, the only way to get heartworms is to be bitten by an infected mosquito. The parasite only affects dogs, cats, ferrets, and other mammals. According to the American Heartworm Society, humans can be infected (by mosquitoes) in very rare cases, but the heartworm cannot complete its life cycle in humans and only causes a benign lesion in the lung.

Myth 9: There's No Effective Natural Prevention

According to Dr. Gerald Wessner of the Holistic Veterinary Clinic in Summerfield, FL, holistic pet parents do have an alternative to traditional heartworm preventive drugs. He has documented success over an 8-year period using heartworm nosodes (a homeopathic vaccine) in conjunction with Paratox (a multi-remedy of homeopathics) and including diatomaceous earth in pets' food.

Myth 10: Puppies and Kittens are Born with a Natural Heartworm Immunity

While mother cats and dogs pass some immunity through the colostrum in their milk, puppies and kittens are not immune to heartworms. In fact, experts recommend beginning prevention habits early. Consult with your veterinarian as to when your young pet may be ready to start on a heartworm preventive regimen.

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  • 10 Heartworm Myths
    04/14/2015 11:08am

    Cannot view any of the '10 Heartworm Myths' ..

  • 04/14/2015 05:07pm

    Neither can I! This is consistently a problem with every "next page" arrow on this damned website.

  • 08/02/2016 01:47pm

    Myth 1: Mosquito Season Occurs the Same Time Every Year

    According to the American Heartworm Society’s latest survey of veterinarians, unseasonably mild winters combined with early springs bring the perfect conditions for an early start to mosquito season. With the unpredictability of the weather in recent years, no particular months or seasons are guaranteed to be mosquito-free.

  • 08/02/2016 01:48pm

    I can read them and would copy here but they will not let me

  • 08/04/2016 10:35pm

    Me neither.

  • Can't see slideshow AGAIN
    04/14/2015 12:23pm

    Yeah me neither, posted this before with other articles with slideshows, the fixes suggested by petmd don't work and I don't have issues watching slideshows on any site but this... love petmd but getting seriously frustrated about seeing info I want to read but can't - like I SOOOO want to read this, but can't so am really disappointed! :(

  • 04/14/2015 12:58pm

    So glad it's not only me :)

  • Slideshow broken
    04/14/2015 03:55pm

    I can't see the slideshow either. The slides don't advance at all.

    Why would you offer up such important information in a user-unfriendly format?

  • Vet practicing homeopathy
    04/14/2015 10:18pm

    I had no problems with the slide show.
    I wonder where in India I could find a vet also practicing homeopathy. Here most run evening clinics that they attend after their State govt job is over for the day.

  • viewing slideshw
    04/14/2015 10:13pm

    i havent been able to view the slide shows for a long time either, i sent them a notice but nothing has happened, they need to fix this, i see im not the only one, whats the sense in having it if no one can see it

  • No slide show advance.
    04/19/2015 04:29pm

    No slide show advance.

  • 10 Myths about Heartworms
    04/22/2015 04:28pm

    It seems that Adobe Shockwave Flash is the problem ...

  • 04/22/2015 04:32pm

    I temporarily 'fixed' my problem by uninstalling Shockwave and re-installed.
    Slideshow is working at the moment.

  • VIAGRA gave us 2 more yrs
    04/22/2015 09:39pm

    One of our dogs got heartworm...following treatment at UC Davis School of Veterinary Medicine they recommended putting her down. They had started her on VIAGRA the night before (this was in 2003) and there was no response so they thought it didn't work...since we refused to put her down in a place that she was not familiar with my husband said no, he would bring her home to her own vet and surroundings. During that 6 hour drive she apparently started responding to the medication - when she got home she actually walked to the lawn to go pee..then came in and drank water/ate food for the first time in 6 days..we decided to keep her through the night instead of calling our vet...next morning she was even more improved and ultimately lived another 2 years...apparently VIAGRA was originally developed for an alternative to Nitro glycerin (for heart problems) but was discovered to have other affects on the human body (males anyway)..our girl had developed Pulmonary Hypertension and the vasodilator was just what she needed to get enough oxygen into her system...like I said we were blessed with two more years - had we followed the vet's recommendation we would have lost that time with her.

  • 05/05/2015 09:44pm

    What a wonderful story. It gave me hope for my little pet. :) I just needed to ask you if "Viagra" is the same meds that men use when they get older? ....& where can I buy this stuff from? Thanks so much for your post. :) Have a super blessed day!

  • They work now
    08/03/2016 02:35pm

    I had no problem viewing the 10 Heartworm Myths