Heartworm Disease: Facts and Myths

Myth #1:

Cats can’t get heartworm disease.

Fact:

Like dogs, cats can get infected with heartworms, but there are two major concerns.

First, it can be extremely difficult to detect heartworms on a blood test in cats. This is because cats with a heartworm infection often have only two or three adult worms. Heartworm tests are simply not sensitive enough to reliably and consistently detect those small numbers of worms.  

Second, cats don’t even need adult heartworms to develop serious problems. Heartworm Associated Respiratory Disease (HARD), for example, is a serious condition that can result from immature heartworms alone. 

Signs of heartworm in cats can vary, too, from a more subtle cough or loss of appetite to fainting or seizures, so staying on top of preventative care for your feline is critical.

Myth #2:

Indoor pets are not at risk for heartworm.

Fact:

Pets that spend more time outdoors will generally have a higher risk for things like heartworm, but because it can be transmitted through a single mosquito bite, even a short bathroom break for your indoor pet makes them susceptible.

Good practices and precautions are your best defense for indoor pets. Mosquitoes can lay their eggs in as little as one inch of standing water, so keeping a dry outdoor space free of any stagnant water will help you prevent the unwanted spread of heartworm.

Myth #3:

Heartworm disease doesn’t occur in dry climates.

Fact:

Heartworm disease continues to be steadily reported in all 50 states. This is because mosquitoes are highly adaptable; some breed and hatch openly during or after rainfall while others reproduce in the standing water found in things like old tires or a birdbath. And since ponds, lakes, and even swimming pools are ideal breeding grounds for mosquitoes no matter the climate, the spread of heartworm really can happen anywhere.

Myth #4:

Preventative heartworm treatment is only necessary in the summer months.

Fact:

While the warm summer months are the preferred environment for mosquitoes, weather conditions across the United States vary widely, meaning that some states may see mosquitoes present year-round. Mosquito species are also constantly changing and adapting to cold climates, so “mosquito season” can fluctuate drastically from one region to another and even from one year to the next.

Myth #5:

Heartworms can be passed directly from one animal to another.

Fact:

Mosquitoes play an essential role in the life cycle of a heartworm and the transmission from one pet to another. Because heartworms undergo an incubation period in a mosquito to become infectious, a pet cannot become infected with heartworm larvae from being near an infected animal, even of the same species. This might sound like good news, but because mosquitoes can quickly and easily move from one animal to another, prevention through medicine is key.