Even Indoor Cats Get Heartworms

Hi everyone! As you know last week I had a scare with Sammy testing positive for heartworm. Now that I have read up on heartworm in cats, I want to spread the word so everyone knows the risks. My vet has always recommended preventative and has posters in the exam rooms about heartworms in both cats and dogs. I chose to take my chances being that my cats are inside and hubby keeps the screens repaired. I do recall having two mosquitoes in the house this past summer though because heartworm crossed my mind when I saw them.

(isn’t Sammy handsome? )

I don’t have a medical background so I am going to give some links to read up on it. I will let you know that they affect cats and dogs in different ways. When a dog gets heartworm it is a death sentence ( unless treated), but with cats it does not always lead to death, but it can. A dog is a natural host for them, but a cat is not so if a cat does get exposed the chances of any worms surviving to the adult stage is less. A cat with them would have 1- 3 on average, but dogs have many more than that.

The mosquito is the nasty critter that spreads them. This is why I assumed my cats were safe because they don’t go outside, but mosquitoes do get inside despite our efforts to keep them out and all it takes is one bite.

There is a very costly and dangerous medicine to kill heartworms in dogs, but this is not an option in cats. If a cat does end up with adult heartworms, the worms can live for 2- 3 years in them. They can cause a respiratory illness resembling asthma. Many cats have no symptoms, but die suddenly.

Here are some excellent resources to learn more about it:

American Heartworm Society ( they have a map showing areas of greatest risk)

VCA page on heartworms in cats

Live Science (article about the importance of diagnosis)

Nova Cat Clinic (great explanation of how this is a lung disease, not heart)

I am going to be using preventative for now on after this scare. And poor Sammy is still not out of the woods because the first test showed he was positive for being exposed, the antigen test was negative, but there needs to be pregnant female worms to make it positive. I plan to have him tested again in a few months because it takes 6 months for them to reach maturity. I know this is all very confusing so please read the links to get a better explanation.

I highly recommend anyone with a cat use heartworm prevention. I am not sure if this is a problem in other countries, but in the USA it definitely is. If your cat already has an illness or is older you may choose not to, you need to discuss the pros and cons with your vet.My niece worked at a vet clinic for 10 years and she said they had a few cases per year of cats with heartworms and usually one death per year. That may not sound like a lot, but no one wants their cat to be the statistic, or any cat for that matter.

Please pray for two of our blogging buddies that are not feeling well. Feel free to visit them and wish them well.

Buddy Budd  Fur Everywhere



79 thoughts on “Even Indoor Cats Get Heartworms

  1. Thank you, Ellen–this is very useful information. Thankfully, we are in a low-prevalence area with a semi-arid climate and few mosquitoes, and Effie is not around any dogs. Still, we will be alert for symptoms.

  2. Hopefully Sammy will continue to test negative but your wise words about prevention are so helpful to everyone. Nobody wants their cat or dog to get heartworm and prevention is the only answer even if they are indoor animals. Open a door and bugs can come inside period! Sammy looks very fashionable (and cozy) in his handsome sweater…….!

    Hugs, Pam (and Teddy too)

  3. Heartworm can be a problem, we got our first cat with heartworm at the shelter recently. We were told to just put her on preventive and the worms themselves would die off in a couple of years, since she is young, preventing more should take care of it.

    Of course, everyone needs to talk to the vet about her/his own pets and take that advice.

    My hope is Sammy does well and that the preventive is all you need for him and the rest of your crew.

    • If she starts to show signs like asthma symptoms then she made need prednisone to help with symptoms until those little suckers die off.

  4. I thought Katie was safe. She isn’t. Sammy darling boy..please. Be safe after this medicine and stay with your mommy and daddy. xoxoxo

  5. My girls are going to the vet today, ironically. They’re really old, though, so I’m not sure what I will do about the heartworm fear for cats. I really like your spark! What a nice idea. Your kindness and generosity warm my heart. Be well!

  6. Thanks for the links, Ellen. Sammy does look handsome in his sweater… I will continue praying that Sammy will test negative. I knew heartworm was an issue but vets in our area felt that cats were at a low risk. I am thinking that is not the case. Any risk is scary.

  7. When Angel Cerise had her heartworms, an ultrasound showed she had five worms. Scariest thing Mom ever saw! She lived to be 17 1/2 years old.

    We got the book and those awesome crocheted toys! Thank you so much!

    Sammy, you look so handsome in your sweater!

    • I am glad Cerise lived a long life despite the heartworms. I am glad you like the book and toys 🙂 Sammy thanks you too ! XO

  8. I wonder if different parts of the USA are more prone to heart worm than others? Still, heart worm in indoor cats isn’t something I’ve thought of much. Thank you for your post.

  9. Lots of good information on heart-worm and kitties. I don’t think I ever even knew about heart-worm when I had cats, but they did go to the vet every year and when needed. Always depended on the vet to make sure everything was covered.

    Prayers for the two kitties that aren’t feeling well.

    Have a purrfect day, Sammy. My best to your wonderful peeps. ♥

  10. shop vac…..dood……lookin good in yur sweater N we hope yur feelin soooooooper grate mega WAY better; thanx for sharin all theze linkz N for de info ♥♥♥

  11. Yep living in the south my vet has always recommended hear tworm treatment for me, I get it from Revolution squirt stuff that combines heart worm, fleas and tick protection.
    Hugs Madi and YES indeedy Sammy is most handsome

  12. It’s really scary.
    I really hope that Sammy will remain negative.
    Than you for all those informations. I just realize that I live in a part of France where it can be a problem. Next time I go to see my vet I will ask her about “Dirofilaria immitis”. I want to know if something has to be done against it.
    Douce soirée

  13. Wow. I had no idea. I feel like I should’ve known – but I figured my kitties being indoor only meant that they were mostly safe. The Boy smokes outside and I noticed with him coming in and going out on a regular basis, we got more mosquitoes inside this year. I refuse to kill most bugs – but mosquitoes are the one exception. Nothing good comes from them! We hope Sammy is clear and healthy.

  14. Thank you for this information. I too have taken my chances and not use any heartworm preventative on the cats. I do think heartworm in cats is becoming more prominent, so I may have to rethink what I am doing. ~Island Cats Mom

    • Yes , you should rethink it, but best to talk to your vet because I know Ernie and Wally have health isssues and may not do well with the preventative.

  15. Sending POTP to Buddy Budd and Melita along with strong positive vibes.
    The information on heart worm is very informative. My mom will be discussing it with our vet when I go for my visit since I’m next in the rotation at our house.
    Hugs…Scout Charles

  16. Continued prayers for you and all of your cats. It is always good to educate yourself as much as possible on situations. Discuss everything with your vet, before making a decision. Then monitor your pet for changes. Of course, each pet is unique and needs to be monitored when healthy. It is never an easy fix. There are always pros and cons, too. Hugs.

  17. Sammy, you are totally rocking that sweater! Heartworms are scary… unfortunately chemicals are also a risk, it’s always a balancing act. Though here in Florida, we are definitely closer to Ground Zero for skeeters than many.

  18. Oh Ellen I am now wondering whether P SH was exposed to Heartworm. He got bitten by mosquitos out back this past Summer. Now I wonder about the URI he had in September. I pray to G-D he did not contract Heartworm. Between my health issues & not being able to afford further Vet care….
    Oh crap I hope Siddhartha henry is not infected 🙁
    ((hugs)) Sherri-Ellen

  19. Oh sigh, we all thought just keeping our cats inside would keep them safe. I always worry that I’ll bring ticks inside from my garden on my clothes too. Thanks for the information and warning, Ellen. I hope handsome Sammy is OK.

  20. Sammy, you look very handsum. We’re sure purrayin’ hard dat you don’t have any of those ole heartworms. Mommy offen wishes she could affurd da purrventative, but alas… Big hugs

    Luv ya’

    Dezi and Raena

  21. Pingback: Even Indoor Cats Get Heartworms - Baptize A Cat?

  22. It goes to show you even after mosquitoes are gone, they can leave a nasty disease. I’m glad you caught it early enough. We’re taking our chances but always on the alert for symptoms. Way too many vet bills lately.

  23. We will continue to pray this doesn’t become an issue for Sammy. Thank you for all the great information and resources! Because Samantha is 15 and already has so many health issues, I don’t think we’ll worry about this for her. But in the future we plan to get barn cats so I will be sure to talk to our vet about it then.

  24. Our Simba died suddenly of what our vet thought was heartworm, because for many months prior to that he was coughing and vomiting a lot. He had gone outside when my 2 year old son let him out by mistake…we will never truly know, and at that time heartworm was not well understood at all in cats.

  25. the information is pretty new in terms of things.. when I was first a cat owner we were told cats weren’t a natural host so we didn’t have to worry about it, but they kept studying it and realized that it is an issue. Preventative is a good idea in areas where heartworms are prevalent

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