Why Do Dogs Get Heartworms And Not Humans

Only mosquitoes carry the ailment, therefore your dogs, cats, and other pets cannot give you heartworms.

The majority of heartworm microfilariae perish upon skin penetration. Heartworms can’t mature and will eventually disappear even if they do find a way into your circulation.

Human heartworms are typically not a severe issue unless they result in discomfort, pain, or other obvious symptoms.

Why can’t people contract heartworms?

Heartworms cannot be contracted by humans from pets. Only the bite of a mosquito carrying the disease can spread heartworms. Heartworms can occasionally be contracted after being bitten by an infected mosquito. However, since humans are not a heartworm’s natural host, the larvae typically move to the arteries of the heart and lungs and pass away before becoming adult worms.

What causes heartworms in dogs?

Heartworms are spread by mosquitoes from an infected animal to your healthy dog. The infected mosquito may also transmit infectious larvae when it bites your dog. These heartworm larvae mature into adult heartworms over a period of 6 to 7 months, leading to serious health problems and even death.

Can humans contract dog heartworms?

Heartworms are a type of parasitic worm known to pet owners as Dirofilaria immitis.

In your dog’s blood, heartworm larvae can develop into adult worms and obstruct important blood vessels. Your dog could develop organ diseases that could be fatal or cause significant injury if left untreated.

Rarely do dogs spread heartworms to people. In actuality, from 1941 to 2005, there were only 81 human instances of heartworm documented. However, it’s important to get treated for heartworms if you or your pet exhibits any signs.

Can dogs contract heartworms from consuming water contaminated with mosquito larvae?

Heartworm in dogs is not brought on by mosquito larvae, despite the fact that they spread the disease. You may relax knowing that even if your dog drank some old water that contained some mosquito larvae, he won’t get the parasite from drinking contaminated water.

How can you naturally protect your dog from heartworms?

Yes, you can safeguard your dog without giving him dangerous medications. even in areas with problematic insects. Giving your dog the yummy heartworm chew every month might not be as easy, but it’s far safer for him.

Heartworm medications aim to destroy the larvae before they mature due to the way that heartworms develop. However, without using any medications, your dog’s immune system may accomplish that. Focusing on the immune system is necessary to prevent heartworm disease for this reason.

#1 Support Your Dog’s Immune System

The immune system of a healthy dog can guard against heartworm infection. Heartworm illness, not heartworms, is what that is. As Dr. Dupree noted, they are not the same.

It implies that your dog might be infected with heartworms. However, they are not required to harm him.

Consider canines that are wild, like wolves, coyotes, or foxes. These creatures are outside all the time. Therefore, they are considerably more likely to contract mosquito bites than domestic dogs that spend their lives mostly indoors. Although studies indicates that wild dogs do not contract heartworm disease, they may have heartworms. And heartworms do not kill them.

Dogs in the wild consume natural foods, which makes them healthier. Additionally, unlike domestic dogs, they are not exposed to medications and pollutants.

So you may improve the health of your domestic dog by leading a natural lifestyle. That implies…

  • Feed an all-natural, raw meat-based diet (not kibble)
  • Cut back on vaccines
  • Use herbal medicines rather than synthetic ones.
  • Use organic methods to avoid ticks and fleas
  • Use no chemicals in your house or garden.
  • Give your dog filtered or fresh spring water.
  • Get him moving frequently.

It’s not too late to start if you aren’t already doing these things. A strong immune system doesn’t just appear in your dog overnight. It’ll take time, but you can speed things up by feeding him herbs and nutrients that stimulate the immune system.

How are canine heartworms prevented?

No. A commercially accessible vaccination against heartworm disease in dogs or cats is not yet available. Research scientists are considering this option, nevertheless. Currently, the only way to avoid heartworm disease is through using preventive drugs as directed by your veterinarian on a regular basis. These medicines can be taken orally once a month, topically once a month, or intravenously once or twice a year. Consult your veterinarian to find the best course of action for your pet. Numerous treatments also have the additional benefit of avoiding other parasites.

Do dogs truly require heartworm medication?

There is a 250,000 to 1 in 50,000,000 chance that a dog will contract heartworm disease each year, which equates to one in 200 dogs.

Find the contradiction in the following list of assertions: Heartworms can be fatal to dogs and cats and cause serious lung illness. People contract zoonotic diseases from heartworms. By giving them medication once a month that also treats numerous internal and external parasites, heartworm illness in dogs and cats can be avoided. Each year, around 250,000 canines are diagnosed with heartworm infections. 1 However, there isn’t any justification for giving dogs preventives all year round; it’s just not necessary.


Let’s now perform some math. There is a 250,000 to 1 in 50,000,000 chance that a dog will contract heartworm disease each year, which equates to one in 200 dogs. You have a one in 200 risk of receiving a cancer diagnosis this year, which is the same likelihood that a dog would have heartworm disease. 2 However, heartworm infection in dogs is almost completely avoidable. Would you take a monthly prescription to avoid developing cancer this year? However, there isn’t any justification for giving dogs preventives all year round; it’s just not necessary.


Let’s now examine the available heartworm treatments. There is no medication authorised to treat heartworm infections in cats, however dogs can be treated with the arsenical melarsomine dihydrochloride. The dosage of melarsomine is 2.5 mg/kg. In mongrel dogs, the LD50 for organic arsenic is 14 mg/kg. 3 Melarsomine overdoses of three can be fatal. 4 The EPA has set the limit for arsenic in drinking water at 10 parts per billion5, or 10 g/L, based on a no-effect risk of 1 to 10,000 to 1 to 1,000,000. You would therefore consume 100 g of arsenic per day, or 36.5 mg of arsenic per year, if you drank 10 L of water each day that contained the maximum permitted level of arsenic. Two injections totaling 250 mg of melarsomine, which has a 37.5 mg arsenic content, are given to a 50 kg dog. To receive the same quantity of arsenic used to cure heartworm illness in a dog, it would take one year of consuming water with high arsenic levels. Therefore, the dose required to eradicate canine heartworms is by no means little. However, there isn’t any justification for giving dogs preventives all year round; it’s just not necessary.


Arsenical therapy is undoubtedly far preferable to the long-term effects of big worms residing in their hosts’ pulmonary arteries. In the wake of treatment, the lungs do improve. 6 The male and female adult heartworms are both around 1 mm in diameter and range in length from 12 to 20 and 25 to 31 cm, respectively. 7 Even if a dog only carries 12 worms—six men and six females—that is still a significant number of worms in the pulmonary arteries.

The worms’ interaction with the pulmonary arteries’ surface results in a persistent illness.

8 In addition to physically rupturing red blood cells, the presence of the worms in the bloodstream causes hemoglobin to be deposited inside of fixed macrophages in the lungs, giving dogs with chronic heartworm infections brown lungs. The development of tiny thrombi that travel deeper into the lungs and ultimately cause chronic lung illness is another effect of villous proliferations on the arteries.

But remember that despite treatment, the worms are in the pulmonary arteries and not the digestive system. After receiving arsenical therapy, the only thing that may happen is that the worms are pushed deep into the lungs, where they eventually die in tightly wound bundles, decompose, and are eliminated by the host’s immune system. Remember that each dead worm is around 20 cm long, so this process takes a while and is not without consequences. However, there isn’t any justification for giving dogs preventives all year round; it’s just not necessary.


Don’t forget to account for nature’s unpredictable behavior. Although it is known that Culex tarsalis mosquitoes may survive for up to two months in temperatures that remain at 77°F9, there is a good likelihood that they could survive for longer in colder climates. More than half of the female overwintering Culex territans mosquitoes investigated survived more than 138 days at 23 F near George Lake in Alberta, Canada. 10 If these mosquitoes are infected with heartworms in October, they might still easily transfer the infection during an exceptionally warm December, like the one we had this year in Ithaca, New York. These mosquitoes will continue to seek blood meals whenever they are about to lay eggs. These microclimate conditions put dogs at danger all year long, which is one of the reasons why the capc guidelines recommend that dogs receive preventives all year long. There seems to be no good reason for a dog to be at risk in a pleasant November or in a warm March, given locally acquired heartworm transmission probably occurs in any state. However, there isn’t any justification for giving dogs preventives all year round; it’s just not necessary.


Maybe we could learn something from our colleagues in human medicine. Mosquitoes that bite sick people spread human lymphatic filariasis, a condition brought on by heartworm relatives. Elephantiasis brought on by the condition is terrible. Small, thread-like worms that inhabit the lymphatics inflict crippling and severely disfiguring sickness on their human hosts. Through “bulk drug administration tactics for disease elimination,” the World Health Organization is leading the effort to eradicate these parasites. 10 The rate of infection in humans and vectors has significantly decreased as a result of these population-wide mass therapies. 11 We can only hope that, in the future, such restrictions on the spread of heartworms would help to lessen the incidence of the debilitating illness that heartworms in dogs bring on.

Professor of parasitology at the Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, is Dwight D. Bowman, MS, PhD.

Does dog feces contain heartworms?

Keeping track of the various ailments, parasites, and illnesses that pose a hazard to your pet can be challenging. Fortunately, we’re here to support you and make sure your pet is appropriately shielded against as many ailments as we can avoid. We debunk 10 common heartworm disease myths in order to clear up the many misconceptions that pet owners have regarding the condition and the harm it poses to animals.

Myth #1: A heartworm-positive dog can infect my dog

A mosquito is required for the spread of heartworms. When a mosquito feeds on the blood of an infected dog, it takes up minute larvae worms, develops them inside the mosquito, and then spreads them to other dogs when it bites them. Although she cannot contract the disease through direct touch with a heartworm-positive dog, mosquitoes may spread it to your dog if it lives with or is close to one that does.

Myth #2: If dogs near my pet do not have heartworm disease, she will not get it

Canine hosts, such as dogs, wolves, coyotes, and foxes, are preferred by heartworms. Although the dogs in your neighborhood may be heartworm-free, mosquitoes can still spread the disease through stray dogs or local wildlife. In pockets of woods, the majority of rural and suburban regions are home to a robust wildlife population, and stray dogs can infect pets in cities.

Myth #3: If my pet has heartworms, I will see them in her feces

Heartworms do not dwell in the gastrointestinal (GI) tract and are not found in feces, despite the fact that many worm kinds, including roundworms and microscopic hookworms, are shed in your pet’s feces. Heartworms are parasites that are found in a pet’s heart and the surrounding big blood vessels, where they significantly impede healthy blood flow and cause substantial inflammation. A blood test, which looks for mature female worms, is the only way to determine whether your pet has heartworm disease.

Myth #4: My pet will act sick if she has heartworm disease

You would anticipate that your pet will notify you right away if she becomes infected with heartworms because they seriously harm the heart, the lungs, and cause a condition that eventually results in death. Unfortunately, until the infection is serious and there has been major damage, pets with heartworm disease don’t exhibit many symptoms. The few larval worms that a mosquito deposits mature in around six months. Unfortunately, your dog may be infected for a year or longer before you see any symptoms until adult worms start to reproduce. Once this happens, worms amass and your dog may exhibit hazy clinical symptoms including lethargy, coughing, and vomiting.

Myth #5: I can stop giving my pet heartworm prevention during the winter

Although mosquitoes are tough, they can appear whenever temperatures increase above 50 degrees, even in the chilly New York winters. In order to prevent your pet from being bitten by an errant January mosquito, year-round protection is safer given the recent mild winters and the unpredictability of the weather.

Myth #6: Skipping a dose or two of my pet’s heartworm preventive is not a big deal

Your pet is susceptible to infection and sickness even if they miss just one dosage of their heartworm medication. Heartworm preventives kill larval heartworms that may have been spread by a mosquito bite and function retroactively. If your pet is bitten by an infected mosquito during the month she does not receive a preventative dose, the larvae worms may survive instead of dying. This is because they are only effective for around one month. The preventive treatment loses its effectiveness once the worms reach a particular stage of development, and they will continue to grow into adult worms.

Myth #7: My indoor pet does not need heartworm prevention

Regardless of whether they spend time outside or not, all pets should take heartworm protection. Mosquitoes undoubtedly enter the building. 25% of cats with heartworm illness are indoor-only pets, according to the American Heartworm Society. To safeguard your indoor pet against mosquitoes that follow you through an open door or squeeze through a hole in your home’s defense, use heartworm prevention.

Myth #8: My pet does not need an annual heartworm test if she receives regular prevention

While it makes fair to assume that monthly preventive results in a heartworm-free status, it’s crucial to test your pet once a year. If you accidently forget to give your dog its prescription, if she spits it out, or if she vomits without your awareness in a backyard nook, your pet may not be protected.

Myth #9: Cats can’t get heartworm disease

Although dogs are the preferred host for heartworms, cats can also be infected and can also get seriously ill. A cat cannot reproduce the few worms that are spread by a mosquito bite, but they can live for up to three years and cause serious irritation. Heartworm-associated respiratory illness (HARD), which is named for the condition’s substantial lung inflammation and asthma-like symptoms, is caused by heartworm infection in cats. Cats with worm infestations may experience collapse and unexpected death as a result of the inflammation the worms cause.

Myth #10: If my pet gets heartworms, she can simply be treated

There is a therapy for canine heartworm disease, but it is time-consuming, dangerous, and expensive. A drug to destroy the adult worms is periodically injected deeply into a dog’s back muscles for the course of the treatment, which normally lasts several months. Additional drugs are given between adulticide treatments to get rid of juvenile worms, reduce inflammation, and kill germs carried by the worms that cause irritation. Activity is limited during therapy to lower the danger of a fatal pulmonary embolism, which can happen if dead worms lodge in a blood artery.

Since there is no medication to kill adult heartworms in cats, treatment focuses on reducing inflammation until the worms naturally die. Since there is no curative treatment for cats, prevention is essential.