Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Heartworm in Cats (Vet Reviewed Signs & Care FAQs)

Share

Sick cat in animal hospital

Heartworms in cats are similar to those in dogs. However, they are difficult, if not impossible, to treat, and the best way to keep your cat healthy is to work with your vet to prevent them. Because heartworms can harm or kill your cat, getting immediate veterinary care can help alleviate the signs.

Your vet can also monitor them to see if they rid themselves of heartworms on their own. So, what signs of heartworms in cats should you be looking for? Keep reading to find out.

divider 3 paws

The 4 Possible Signs of Heartworm in Cats

1. Respiratory Problems

Heartworms don’t stay in the heart. They travel throughout the vascular system, and the first place they often end up is in the lungs, where they can restrict blood flow and cause inflammation.

You may notice intermittent coughing or signs that your cat has trouble breathing, like breathing with their mouth open. These signs are not unique to heartworms and should always be evaluated by your veterinarian for a proper diagnosis, but if heartworms are causing them, they must be addressed early.

When respiratory issues develop from heartworms, it’s called  Heartworm-Associated Respiratory Disease or HARD.1 While it can be challenging to treat heartworms in cats, your vet may be able to address the respiratory problems, making it easier for them to breathe.


2. Lethargy

tired sick cat lying on bed
Image By: Natata, Shutterstock

If your cat seems tired and uninterested in their toys or other activities, it’s a sign that they should see the vet. Lethargy, like respiratory problems, is not a definite sign of heartworms in cats but can indicate that something is wrong and should be diagnosed and treated.

In combination with other signs on this list, it could mean that your cat has contracted heartworms, in which case your veterinarian is the best resource for advice and treatment. You know your cat best, so trust your instincts if they aren’t acting like themselves.


3. Weight Loss

Heartworms in cats can cause general unwellness that can lead to weight loss. Coughing associated with the disease can also precipitate vomiting. You should take these concerns to your vet, who can determine the underlying cause and suggest appropriate treatment.


4. Death

Death due to heartworms can come years after a diagnosis, while your cat has been living a somewhat normal life before succumbing to it. It can also come on suddenly, without knowing your cat even had them. In that case, the only way to know that heartworms are to blame is for your vet to perform a post-mortem exam to determine the cause of an unexpected death.

Because the sudden death of a pet is shocking and heartbreaking, knowing what happened can provide closure and peace of mind, which is why some pet parents choose this option. It may also help prevent other pets in the home from getting sick.

divider 3 paws

FAQs About Heartworms in Cats

How Are Heartworms in Cats Diagnosed?

Many of the signs above can also indicate other cat diseases. Therefore, it is crucial to pinpoint the exact cause so it can be treated in the best possible way and improve your cat’s quality of life. There are several ways to diagnose heartworms in cats.

If your vet suspects heartworms, they will likely run blood tests for heartworm antigens. X-rays and a cardiac ultrasound may also show the presence of heartworms.

You are free to use this image but we do require you to link back to Catster.com for credit

Can Heartworms Be Treated?

The medications used for dogs cannot be used for cats, and there is no effective treatment to cure heartworms in cats. Some cats may rid themselves of heartworms on their own after a few years, and your vet will recommend testing every 6 to 12 months or more often if they display concerning signs.

While there isn’t a way to permanently cure heartworms in cats, your vet can treat the side effects to make your cat more comfortable.

Can They Be Prevented?

Even indoor cats are susceptible to heartworms, but if mosquitos are prevalent in your area or your cat is frequently outside, you must work with your vet to prevent heartworms. A monthly treatment can be a topical medication or pill, but it should be given on a strict schedule to ensure your pet is protected.

You’ll need a prescription from your vet to purchase heartworm prevention medications, or you can buy them directly from their clinic in most cases.

divider 3 paws

Conclusion

Heartworms in cats can be serious, and if you see your cat behaving strangely or showing signs of distress, get them to a vet immediately. If they determine that heartworms are the cause, you can work closely with them to ensure your cat remains as healthy as possible with the hope that they can clear the worms on their own. If not, remain vigilant in watching for signs of their condition worsening so you take them to the vet promptly.

See Also:


Featured Image Credit: Kachalkina Veronika, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.




How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.


Catster's Digital Magazine is Back!

Vet-approved health & behavior advice

Real cat stories & community features

Chatting with Devin About Here! Have a Kitten, Fostering, & Why Two Are Better Than One | Chatty Cattys, Episode 29

In this episode of Catster’s Chatty Cattys podcast, Nicole & Dr. Karyn sit down with Devin, the founder and one-woman show behind “Here...

Decoding The Cat Loaf: What It Means and When to Worry

Few cat behaviors have captured the internet quite like the loaf. Paws tucked neatly beneath the body, tail wrapped in, perfectly rectangular. As...

Your Cat Isn’t Picky – Their Nose Is Just Bored

If you’ve ever sighed while scraping uneaten cat food into the trash, you’re certainly not alone. Many cat owners know the routine: their...

Ask Dr. Paola – Help! My Kitten Won’t Use the Litter Box! (July 27, 2026)

Welcome to our “Ask Dr. Paola” series, where every Monday we bring expert advice straight from Dr. Paola Cuevas (MVZ) to help our...

More related

100+ Hawaiian Cat Names: Ideas for Laidback Kitties

Hawaii is full of amazing traditions and delicious cuisine. It is home to the Hula, and everyone is greeted with “aloha.” Their laidback...

How Cats Help Humans Across the World Get Through Lockdowns & Life

Those of us who are diehard cat lovers already have a good idea of how cats help us. When you have a cat...

Cats Peeing on Shoes: 7 Vet Reviewed Reasons & How to Stop It

Nothing is worse than slipping your feet into a pool of cat pee—in your own shoe. If your cat has made a habit...

What Is a Community Cat? Facts & FAQ

Whether you live in a city or a rural area, you may have spotted large groups of cats living together outdoors that don’t...

Keep reading

Can You Use Kitty Litter for Oil Spills? Alternative Uses, Tips & Tricks

Kitty litter has several uses other than making it possible for cats to use the bathroom indoors, including providing emergency traction to help cars get moving on snowy days and cleaning up oil spills. Kitty litter is handy because it...

biodegradable litter

Why Does My Cat Keep Licking Their Lips? 5 Vet Reviewed Reasons

Cat’s licking their lips can be a very common behavior, but now every time you look over they seem to be doing it. Maybe you wrote this as normal, but they just won’t seem to stop. So, if they didn’t...

grey cat just finished eating

Pros & Cons of Using Cat Diapers: Is It Right for Your Cat? Vet-Reviewed Info

There are a few reasons that a cat can wind up needing to wear a diaper, from having incontinence to spraying or from other medical or behavioral issues. In such circumstances, a cat diaper might be necessary. The type of...

black-cat-wearing-diapers

Can Cats Eat Sesame Seeds? Vet Approved Nutrition Advice

Sesame seeds are fairly nutritious for humans and many other omnivores. But what about cats? Can cats eat sesame seeds? Although sesame seeds don’t contain any toxic or harmful properties, they are not a food that’s easily digestible for cats....

Can Cats Eat Sesame Seeds

Can Cats Eat Granola Bars? Vet-Reviewed Health Facts & FAQ

Granola bars are a popular snack for kids and hikers alike. If your cat is a beggar, you might wonder if it’s okay to share as you munch. Unfortunately, cats shouldn’t eat granola bars because they aren’t healthy for them,...

Can Cats Eat Granola Bars

Why Is My Cat So Hyper All of a Sudden: 8 Possible Reasons (Vet Reviewed)

For some cats, it is not rare that they will have a moment of wildness and suddenly charge around the house. For others, it can be a surprising and sudden occurrence. While it might simply be a case of your...

cream tabby maine coon cat playing water

Will Barn Cats Kill Chickens? The Interesting Answer (Vet-Approved)

A barn cat isn’t a specific cat breed but a term used to describe a cat that usually lives outdoors, either as a pet or a feral animal, on agricultural properties, usually sheltering in buildings. They’re also known as farm...

chicken looking at the camera in the yard

Can Cats Drink Goat Milk? Vet-Reviewed Facts & FAQs

There are plenty of health benefits associated with drinking goat milk in humans, so it’s only natural to wonder about goat milk for cats and if it’s safe to allow them to drink it. So can cats drink goat milk?...

Can Cats Drink Goat Milk

Love Cats? So Do We! Join the Catster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Catster Email Newsletter

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.