Monday, June 11, 2012

Monday Medical Issues: Heartworms

Just a few days ago, a fellow shelter volunteer posted that she’d taken her cats in for their annual exams, only to find out that one of them tested positive for heartworm antibodies.

She posted this news as a warning to friends and fellow volunteers: when choosing flea medication, be sure to choose a brand that will protect your cat from heartworms as well.

Copyright American Heartworm Society
Here in the Midwest, heartworm in cats is on the rise.

Just a few years ago, it was unheard of to think a cat was susceptible to heartworms.

In fact had you asked me back then, I would have (mistakenly) voiced the opinion that heartworms are a canine
disease – not feline.

I could not have been more wrong.

I feel for my friend and fellow volunteer. I had the very same scare with Allie last summer. I was never more shocked than when I heard my vet tell me he wanted to test Allie for heartworms. 

Fortunately for us, Allie tested negative. The poor girl got preventive medication slapped on her so fast she didn’t know what hit her! Unfortunately for my friend, her kitty is already infected.

Heartworms are a lot more serious in cats and small dog breeds than they are in large dogs. And unfortunately for us cat owners, there is no treatment that will get rid of them. And heartworm medication for dogs is fatal to cats. So for kitties, this is a disease with no cure. All  a vet can do is treat the symptoms in your cat for as long as the heartworm lives.

The reason it's so dangerous in cats and very small dogs is because of the stress the heartworm places on the animal’s body. A heartworm will take up residence in the heart and pulmonary system, where it will grow to full size and reside for roughly three years before its life cycle ends. During that time, a cat or small dog will often exhibit asthma-like breathing problems.

At its time of death, the heartworm then sheds a protein that places additional stress on the animal’s system, which can lead to heart failure.
Often there is no warning: the only symptom is sudden death.

Dogs and cats are infected with heartworms by being bitten by a mosquito. Before you say, “but my cat is indoor-only!” let me share with you the single statement that made me into a believer: it only takes one.

Yes, my cats are indoor-only. But despite the care I take with keeping the doors shut (after all, I wouldn’t want the cats to get out now, would I?) there is invariably the mosquito or three that manage to get into the house during the summer. And with the mild winter we’ve had this year, I spotted our first mosquitos back in February.

My friend’s vet gave her the same information our vet gave me when examining Allie: heartworms in cats is on the rise. Both vets testified to having treated more cats for heartworm in 2011 than they did dogs.  We assume this is mainly because people aren’t used to treating their indoor cats with heartworm preventive medication and so the cats aren't protected

Fortunately, protection is simple and effective – and since the medication is combined with flea and tick medication,  you’re still dealing with the application of a single monthly dose.

If you have any questions about heartworm please don’t hesitate to seek more information from your vet.  And remember: never ever ever give heartworm medication meant for a dog to your cat – it can be fatal!


  1. One of the cats who came before us was a heartworm survivor back in the 1990's, when it was virtually unheard of in cats. It was confirmed with an ultrasound. Really spooked Mom out seeing those evil worms on Cerise's heart. The vet always called Cerise their miracle kitty because she survived. They really didn't know what to do but they put her on antibiotics and steroids for awhile. Cerise was an indoor kitty, but mosquitoes can get in the house.

  2. I had no idea that cats were susceptible to heartworm! We treat Rio for heartworm monthly but my vet has never mentioned the cats. I going to the clinic today to pick up food, I will definitely ask about this while I'm there!!!

  3. Hi that was very interesting and my flea medication covers me for the problem we have here which is lungworm from slugs and snails and with all the rain we have been having they are everywhere. Thank you very informative. Have a happy Monday.
    Best wishes Molly

  4. Oh, this is so scary! But knowledge and prevention are so valuable. And now we know. Thank you, friends!

  5. Skeery! We'll have our Mommy look into this immediately. Thanks fur the info!

  6. You just scared the beejesus out of my human, even though we are in a low risk area! Now she wants to get ALL us cats checked out. Ick, but I guess it has to be done.

  7. That is important news! Kitties can use Revolution (topical), Heartgard soft chews for cats, or Interceptor chewable tablets in the cat dose. Unfortunately, Novartis is still not manufacturing Interceptor so that is hard to find.

    1. Yes! We use Revolution at our home. Didn't know Heartguard came as a chew. We think we would probably spit that out though...

  8. We agrees! Heart worm was first found in Canada where we lives. Even though we only visited here in the summers for the last 10 years, Mommy and Daddy made sure we was all (cats included) taking heart worm medications. Our Calgary vets used to say us cats did not need it but wes gots it anyway. One once of prevention is worth one pound of cure!

  9. We will make sure that we've been tested fer heartworm!

  10. very good info...I never go out and am only anifamily member...but impawtant for dogs and cats to know about


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