Myths about Heartworms

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.


Laurelwood Animal Hospital

9315 SW Beaverton-Hillsdale Highway
Beaverton, Oregon 97005

Phone: (971) 244-4230
Fax: (503) 292-6808

E-mail: [email protected]