April, National Heartworm Awareness Month, is the perfect time to brush up on your knowledge of the serious disease this spaghetti-shaped parasite can cause your pet. To help you do that, our Krichel Animal Hospital team is busting myths and sharing facts to help you protect your furry friend from heartworm disease or obtain the best possible treatment if they contract this condition.

Myth: Dogs are the only pets that get heartworm disease

Truth: Dogs, cats, and ferrets are all susceptible to heartworm disease, which can be fatal if left untreated. Some wild animals are vulnerable, too. Dogs are natural heartworm hosts, and these parasites can spend their entire 5-to-7-year life cycles inside an affected dog, damaging their heart. In cats, adult heartworms only live for 2 to 4 years, and the disease they cause affects the lungs more than the heart. Veterinary researchers refer to this condition as heartworm associated respiratory disease (HARD). 

Myth: Pets only need heartworm protection during the spring 

Truth: The American Heartworm Society (AHS) says heartworm season is year-round. Although the mosquitoes that cause the disease proliferate when the weather is warm, pets need protection throughout the year. To protect your pet from this year-round disease threat, our Krichel Animal Hospital team will prescribe the heartworm preventive that will be most effective for your pet.

Myth: Only pets in certain parts of the country have a heartworm problem

Truth: Iowa has historically had lower heartworm disease rates than other parts of the United States that are warmer and more humid, but you must not let your guard down. In its 2024 Annual Pet Parasite Forecasts, the Companion Animal Parasite Council (CAPC) cautioned veterinarians in the Midwest about heartworm infection’s increasing risk and encouraged them to discuss this issue with their clients. “This is particularly important in southern Indiana, central and southern Illinois, southern Iowa, Kansas, and Lower Michigan and Ohio in the Great Lakes region,” the CAPC said.

Myth: Indoor pets are safe from heartworm disease

Truth: Living indoors lessens a pet’s contact with mosquitoes but doesn’t eliminate their heartworm disease threat. An infected female mosquito can enter your home through an open door or window and bite your pet, transmitting heartworm disease to your furry pal.

Myth: Pets can transmit heartworm disease to each other

Truth: This is impossible, with one exception. Since only an infected mosquito can give a dog, cat, or other animal heartworm disease, pets of the same or another species cannot infect each other directly. However, while an infected mother dog cannot directly transmit heartworms to her unborn puppies, microscopic baby worms—microfilaria—can travel through her bloodstream into the puppies. Fortunately, a puppy’s first heartworm prevention dose typically eliminates these worms. Until the worms are gone, however, those puppies could infect a mosquito or an unprotected dog.

Myth: Heartworm disease is easy to diagnose and treat in pets

Truth: Heartworm disease diagnosis can be challenging. With cats, symptoms commonly seen in the disease’s first stage can mimic feline asthma or allergic bronchitis. Dogs and cats with early heartworm disease have breathing problems and may cough, have little appetite, lose weight, and be lethargic. Cats may also gag or vomit. Unfortunately, these signs are not unique to heartworm disease. 

In dogs, heartworm disease signs don’t appear until heartworms start living in a dog’s lungs and heart. Our veterinarian diagnoses the condition by performing blood tests, a heart ultrasound, and chest X-rays. For cats, diagnosis involves a complete blood count and blood chemistry profile, chest X-rays, other tests, and sometimes ultrasound.

Dogs’ heartworm disease treatment is 98% effective. Treatment involves a series of melarsomine injections, the only drug the U.S. Food and Drug Administration (USFDA) has approved for this purpose. Six months after the injection series, our veterinarian does a follow-up test to ensure a treated dog’s heartworms are gone. 

The outlook is not as good for cats with heartworm disease. They cannot receive the medication used for dogs because it is too strong for them to tolerate. However, cats sometimes throw off the infection on their own.

If your dog or cat is showing any of the heartworm disease signs mentioned above, contact our Krichel Animal Hospital team.