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.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money


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

The Surprisingly Simple Ways to Help a Cat With Hairballs

Cats spend an astonishing amount of time grooming. It is part hygiene routine, part comfort ritual, and part instinct that traces back generations....

What a CATastrophe! A Tire-ing Ordeal For a Pony in the UK

As you would expect, our weekly news updates are usually centered around feline topics – we are a cat care website after all...

Ask Dr. Paola – Help! My Cat Has Stopped Eat His Wet Food! (June 1, 2026)

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

Chatting About Fake News in the Pet World, AI Again, and New Age Journalism | Chatty Cattys, Episode 23

Navigating the modern digital landscape requires a sharp eye to distinguish fact from fiction. In this episode of Catster’s podcast, Chatty Cattys, Nicole...

More related

How Much Does It Cost to Own a Toyger Cat? 2026 Pricing Guide

If you’ve ever seen a Toyger, you’re unlikely to forget the experience. These gorgeous creatures are often referred to as Toy Tigers. In...

Zelda Loves Bailey, But HATES Being Brushed

Hi, I’m Dr. Karyn! Read my introduction to learn more about me and meet my five hilarious cats: Clutch, Cyril, Alex, Zelda, and...

Why Do Cats Like Crinkly Things? 5 Possible Reasons & Risks

Cats are intrigued by objects that make a crisp, crackling sound. Something about their curious personalities makes the compelling sound of a crinkly...

How to Keep Litter Boxes from Smelling: 12 Vet Approved Tips

A common goal among cat owners is keeping the litter box smell to a minimum. This can pose a bit of a challenge,...

Keep reading

6 Best Paper Cat Litters in 2026 – Reviews & Top Picks

When searching for the perfect cat litter, you’ll want to find one that’s good for your cat’s health. You may also be worried about how environmentally safe your cat litter is. If you’re currently using a clay-based litter but have...

black and white cat stepping in the litter box

Why Do Cats Groom Humans? 8 Vet Reviewed Reasons

You can be sitting on the couch and scrolling on your phone when, all of a sudden, you start to feel an unusual feeling on the top of your head or arm. Your cat is licking you a lot lately,...

cat sitting behind the man licking his head

Why Is My Cat Only Eating Treats and Not Their Food? 4 Likely Reasons

Oh no! Your cat, who used to be such a good eater, is now ignoring their full bowl but won’t stop meowing for treats. What gives? Well, your cat may just be acting like a kid who only wants to...

calico cat having treats

Will a Cat’s Whiskers Grow Back If They’re Cut Off? Vet Approved Facts & Risks

Prickly and cute, your cat’s whiskers aren’t merely adorable accessories. They are more like highly specialized antennae that guide your cat around the house and help them estimate tight squeezes and high jumps. Without their whiskers, your cat would be...

close up of cat whiskers

My Cat Is Not Eating But Acting Normal, What’s Wrong? 7 Vet-Reviewed Issues

It is understandable to feel worried if your cat is not eating much but acting normal. Although cats can be finicky about mealtimes and their food preferences, a poor appetite could indicate that something is wrong. There are various reasons...

vet examining the sick cat with stethoscope

Can You Put Baking Soda in Cat Litter? Vet Approved Facts & Safety Advice

Cat ownership changed forever when kitty litter was invented in 1947. You didn’t have to let the family pet outside to do their business anymore which was a relief for many pet owners. Absorbent clay did the job, but it...

woman in a yellow sweater with jar of baking soda

Does My Cat Hate Me? Signs, Causes & What to Do About It (Vet-Verified)

Cats don’t really feel hatred, but they can be scared, irritated, stressed, anxious, or even in pain. And these states of mind can make it seem like your cat hates you based on your interpretation of your cat’s actions. Whether...

Woman giving a grumpy persian cat a kiss on the cheek

Can Cats Eat Chorizo? Vet-Reviewed Facts & FAQ

If you enjoy sausages and salami, chances are that you enjoy chorizo. If you’ve been adding chorizo to your meals on occasion and your cat has been eyeing it with interest, you might wonder if it would be okay to...

Can Cats Eat Chorizo

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.