Hey, so you're probably here because you've heard about heartworm in dogs and started wondering—can cats get heartworm too? I remember when I first asked my vet that question years ago. I had this image of heartworm as a dog-only thing, but boy, was I wrong. It turns out, yes, cats can absolutely get heartworm, and it's way more complicated than I thought.
Let's get straight to it. Heartworm disease is caused by this parasite called Dirofilaria immitis. Mosquitoes are the culprits—they bite an infected animal, pick up the baby worms (microfilariae), and then pass them on when they bite another animal. For a long time, people assumed cats were safe because they're not the natural host, but research shows that's a dangerous myth. In fact, studies suggest that up to 10% of cats in high-risk areas might be exposed. That's not a huge number, but if it's your cat, it feels massive.
What's tricky is that heartworm in cats behaves differently than in dogs. Dogs are like a perfect home for these worms—they can grow into adults and reproduce easily. Cats? Not so much. Their immune systems often kill the larvae before they mature, but sometimes a few worms make it to the heart or lungs. Even one worm can cause serious problems, and there's no approved treatment for adult heartworm in cats. That's why prevention is such a big deal.
How Do Cats Actually Get Heartworm?
It all starts with mosquitoes. If you live in a place with lots of mosquitoes, like the southeastern U.S., your cat is at higher risk. But here's the thing—even indoor cats aren't safe. Mosquitoes can sneak inside through open doors or windows. I've seen it happen with my own cat, Luna. She's strictly indoors, but one summer, we had a mosquito problem in the house, and I freaked out. My vet told me that indoor cats account for about 25% of heartworm cases. That blew my mind.
The process goes like this: a mosquito bites an infected animal (usually a dog, but sometimes wildlife), then bites your cat. The larvae enter the cat's body and migrate over several months. They end up in the blood vessels around the heart and lungs. Unlike dogs, where worms can live for years, in cats, most worms die within 2-3 years. But when they die, they can cause inflammation and blockages that lead to sudden death. It's scary stuff.
Risk factors include living in endemic areas, lack of prevention, and season—mosquito season is worst in warm, humid months. But I've heard vets say that climate change is making it a year-round concern in some places.
Symptoms of Heartworm in Cats: What to Watch For
This is where it gets tricky. Symptoms can be super subtle or mimic other diseases. Some cats show no signs at all until it's too late. I've talked to owners whose cats seemed fine one day and collapsed the next. It's heartbreaking.
Common symptoms include coughing (often mistaken for asthma), vomiting, lethargy, and weight loss. Sometimes, it's just a general "off" feeling. More severe cases can involve difficulty breathing or sudden death due to lung damage. I remember a friend's cat who started coughing after exercise—turned out to be heartworm-related respiratory disease. They caught it early, but it was a wake-up call.
Here's a quick list of signs that should raise a red flag:
- Persistent cough or wheezing
- Vomiting that doesn't link to food
- Loss of appetite or energy
- Rapid breathing or open-mouth breathing
If you notice any of these, don't wait—see a vet. Diagnosis isn't straightforward either. Blood tests can help, but they're not perfect. Antigen tests might miss infections if there are only male worms or low numbers. Antibody tests show exposure but not active disease. X-rays or ultrasounds are often needed to confirm.
| Symptom | Frequency in Cats | Notes |
|---|---|---|
| Coughing | Common | Often confused with asthma or allergies |
| Vomiting | Moderate | Can be intermittent |
| Lethargy | Very common | Might be subtle and gradual |
| Sudden collapse | Rare but severe | Usually in advanced cases |
Diagnosis and Treatment: Why It's So Hard for Cats
Diagnosing heartworm in cats is a puzzle. Vets often use a combination of tests because no single test is reliable alone. The antigen test looks for proteins from adult female worms, but if there are only males or just one worm, it might come back negative. The antibody test indicates exposure but doesn't confirm an active infection. Imaging like X-rays can show changes in the heart and lungs, but it's not definitive.
Treatment is where things get really frustrating. Unlike dogs, there's no FDA-approved drug to kill adult heartworms in cats. The medications used for dogs are toxic to cats and can cause fatal reactions. So, vets focus on managing symptoms and preventing further damage. This might include corticosteroids to reduce inflammation or bronchodilators for breathing issues. In severe cases, surgery to remove worms might be an option, but it's risky and expensive.
I've heard stories from vets about cats who survived with supportive care, but it's a long road. Prevention is honestly the best approach. If you're wondering, "Can cats get heartworm and survive?" Yes, some do, but it's often with lasting health issues.
Prevention: The Only Real Way to Protect Your Cat
Prevention is a no-brainer once you understand the risks. There are several FDA-approved preventatives for cats, like topical treatments (e.g., Revolution, Advantage Multi) or oral medications (e.g., Heartgard for Cats). These are usually given monthly and are highly effective if used consistently.
Cost varies—topical treatments might run $10-$20 per month, while oral options can be cheaper. But compared to treatment costs, which can hit thousands, it's a smart investment. I use a topical on Luna year-round, even though she's indoors. My vet recommended it because mosquitoes are unpredictable.
Here's a quick comparison of common preventatives:
- Topical treatments: Easy to apply, also protect against fleas and other parasites. Downside: can be messy if your cat hates it.
- Oral medications: Often palatable, but some cats are picky eaters. Might require hiding in food.
- Injections: Less common for cats, but ProHeart is an option for dogs—nothing similar for cats yet.
Another thing—environmental control helps. Use mosquito repellents safe for cats, like those with permethrin (but be careful, as some are toxic to cats). Keep screens on windows and avoid standing water in your yard.
Common Myths About Heartworm in Cats
There's a lot of misinformation out there. Let's bust some myths:
Myth 1: Indoor cats are safe. Nope—mosquitoes get inside. I've seen cases where apartment cats got infected.
Myth 2: Heartworm is only a dog problem. Wrong again. Cats are susceptible, even if the disease manifests differently.
Myth 3: Prevention isn't needed in cold climates. With warmer winters, risks are spreading. Vets in northern states are seeing more cases.
These myths can lead to complacency. I've met owners who only learned the truth after their cat got sick.
Frequently Asked Questions
Can indoor cats get heartworm?
Yes, absolutely. Mosquitoes can enter homes through doors, windows, or gaps. About a quarter of reported cases are in indoor-only cats. Don't assume your cat is safe—prevention is key.
What are the first signs of heartworm in cats?
Early signs are often subtle: occasional coughing, reduced activity, or mild vomiting. It's easy to brush them off, but if they persist, get your cat checked. Early detection can prevent worse outcomes.
Is there a cure for heartworm in cats?
No cure for adult worms. Treatment focuses on managing symptoms and supporting the cat's health. Prevention is the only reliable way to avoid the disease.
How common is heartworm in cats?
It's less common than in dogs, but prevalence varies by region. In high-risk areas like the Gulf Coast, infection rates can be significant. Even in lower-risk zones, cases occur regularly.
Can cats get heartworm from other cats?
No, direct transmission doesn't happen. Mosquitoes are required to spread the parasite. So, your cat can't catch it from another cat directly.
Final Thoughts
So, can cats get heartworm? Definitely yes. It's a real threat that many owners overlook. The good news is that prevention is easy and effective. Talk to your vet about the best option for your cat—don't wait until it's too late. I've learned that being proactive saves a lot of heartache down the road.
If you have more questions, drop them in the comments below. I'm not a vet, but I've spent years researching this stuff and talking to experts. Stay informed and keep your furry friends safe!