8 Common Myths About Heartworm Disease

Heartworm is a serious, but preventable, condition caused by an internal parasite referred to as Dirofilaria immitis. Both cats and dogs can get heartworm disease, according to the U.S. Food and Drug Administration, although cats are not as susceptible to the infection as dogs.

Without treatment, heartworm disease can be a potentially fatal condition. Heartworms are generally transmitted by mosquitoes, which carry heartworm larvae (microfilariae) from an infected animal host to another animal. The larvae migrate through the animal’s tissues, eventually reaching the heart and pulmonary arteries. These parasites put stress on the animal’s heart and cause inflammation of the lungs and blood vessels.

While the seriousness of heartworm disease is indisputable, there are many misconceptions that surround these parasites. If you are concerned that your pet may have heartworm disease or want to know how to best protect your cat or dog from heartworms, check out these debunked myths about heartworm disease.

Myth #1: Heartworm disease only develops in warm climates

While heartworm disease is more prevalent in warm climates, you don’t necessarily need to live somewhere warm for your pet to be at risk. Heartworms are transmitted by mosquitoes, meaning any place that has mosquitoes can have these parasites. In fact, heartworm infections have been reported in all 50 states in the U.S.

Myth #2: Indoor pets are not at risk for heartworms

Some pet owners are under the misconception that if their cat or dog is exclusively an indoor pet, they are not at risk for heartworm disease. While having an indoor pet significantly reduces your pet’s odds of developing heartworms, there is still a chance that your cat or dog could develop this disease. Mosquitoes can find their way indoors through open windows or doors, and just one bite from an infected mosquito is all it takes to develop an infection.

Myth #3: Heartworm is rarely a fatal disease

Your pet getting a parasite may not seem like a big deal, but the consequences of this disease are more serious than you may think. Heartworm disease can be a devastating condition that impacts the lungs, heart, and pulmonary blood vessels. When these parasites migrate into the body, they create an inflammatory reaction that can cause permanent damage to the lungs and blood vessels. Symptoms generally start with a cough and can progress to fatigue, weight loss, difficulty breathing, and even death.

Myth #4: Heartworm disease is easily detectable

Signs of heartworms include a persistent mild cough, weight loss, fatigue after moderate activity, reluctance to exercise, and decreased appetite. As the condition progresses, a pet may also develop the appearance of a swollen belly due to excess fluid in the abdomen. Ultimately, a pet may develop heart failure and succumb to the disease. However, these signs do not always present as soon as your pet is infected. Once bitten by an infected mosquito, heartworm infection is generally not detectable for six months.

Myth #5: Pets on heartworm prevention don’t need to be tested

If your pet takes regular heartworm preventatives, you may believe that periodic testing isn’t required. Although preventative heartworm treatments are highly effective, they do not guarantee that your pet will not develop heartworms. As the early signs of heartworm infection can be asymptomatic, it is important to have your pet undergo annual testing. Fortunately, pets that do test positive while on a heartworm preventative are less likely to be infected with a large number of heartworms.

Myth #6: Heartworms can be seen in an animal’s feces

There is a common belief that heartworms will appear in an animal’s feces if they are infected; however, this isn’t true. The confusion lies with the different types of worms that a pet can develop. Other worm types, such as tiny hookworms and roundworms, can leave the body in an animal’s feces. Heartworms, on the other hand, do not live in the gastrointestinal (GI) tract, meaning they will not usually be found in a pet’s feces. Instead, heartworms live in the heart and surrounding blood vessels.

Myth #7: It’s okay to miss a month of heartworm preventative

One mistake that pet owners should never make is missing a month of heartworm treatment. Heartworm preventatives are generally given to pets as a once-a-month treatment to keep heartworms at bay. However, since heartworms are a year-round risk, it is important not to miss a single treatment, especially during the warmer months of the year.

Myth #8: Heartworms can be spread from pet to pet

If your pet has been diagnosed with heartworms, you may be concerned about other pets in your home and their risk of acquiring the disease. Fortunately, heartworm disease is not contagious. It is only spread through the bite of an infected mosquito. Another dog or cat cannot catch the disease simply from being near an infected animal. 

Keep Your Pet Heartworm-Free with Heartworm Preventatives

While heartworm treatments are available, the treatment process can be risky, lengthy, and expensive. The best thing that a pet owner can do to prevent their pet from developing heartworms is to administer monthly heartworm preventatives prescribed by a veterinarian. It’s also important to undergo annual testing to rule out heartworm disease.