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Heartworm Disease in Cats

 by wai on 15 Jan 2014 |
5 Comment(s)

Until recently, most experts would say that cats did not get heartworms.  Over the past few years, research has begun to show that heartworms are much common in cats than was previously thought. 

Prevalence of Heartworm in Cats

There have been laboratory confirmed cases of heartworm in cats in all 50 U.S. states. One researcher who presented at a 1998 heartworm symposium performed random blood tests in cats and found that heartworm disease was more common than feline leukemia (FLV) and FIV or feline AIDS.  Anywhere that dogs are at risk for heartworm, cats are now also considered to be at risk.  

This apparent increase in feline heartworm infection is actually a sign of better detection and understanding of the disease.  Cats may develop only one or two adult worms and, as a result, older heartworm tests that worked on dogs may not be sensitive enough to identify a heartworm infection in a cat. In addition, heartworm disease in cats may be misdiagnosed due to the lack of awareness of the prevalence of the disease as well as the different symptoms that cats develop.

Symptoms of Feline Heartworm Disease

Heartworm in cats often presents differently than in dogs.  Respiratory symptoms, such as coughing and difficulty breathing, are common in cats with heartworm and may be misdiagnosed as asthma.  These symptoms, along with vomiting, weight loss, lethargy, and loss of appetite, may become a chronic disease.  Heartworms can also cause neurological symptoms, seizures, fainting, and death in cats.

Treatment of Heartworm Disease in Cats


Heartworm treatments that work on dogs are dangerous in cats. As many as 70% of cats will die if canine treatments are used.  The best practice for cats with heartworm is to treat the symptoms and allow the adult worms to die a natural death over the course of a couple years. In some cases, the inflammation that occurs when the heartworms die may be life threatening for the cat. 

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Prevention of Heartworm

There are medications available that can prevent heartworm in cats.  If you have a dog and your veterinarian recommends seasonal or year-round heartworm protection, ask about prevention for your cat too.  Heartworm is extremely common in the southeastern U.S. year round and many other parts of the country have a risk of heartworm, especially during warm months.   If your vet is not familiar with the risks of feline heartworm disease, there are guidelines put out by the American Heartworm Society that can help you and your vet make an education decision.

Heartworm and Indoor Cats

It is not just outdoor cats that are at risk of heartworm.  One study found that about 28% of cats that were diagnosed with heartworm were indoor-only cats.  Some researchers theorize that indoor cats may actually be at increased risk since they do not have a built up immunity.  Cats may particularly be at risk if they lie against window or door screens as many indoor cats enjoy doing.  If you live in an area that has a high risk of heartworm disease, consult with your veterinarian about the need to treat your indoor-only cats. 

Heartworm disease in cats is still not completely understood and more research is needed into the prevalence, symptoms and treatments.   In addition, many veterinarians are not aware of the latest research and may not regularly recommend heartworm preventatives for cats.



cynthia - Comment
cynthia16 Jan 2014Reply
I live in australia. Bout 11 years ago my cat presented with these symptoms. I was extremely lucky that I had a very knowledgeable vet who diagnosed my boy with heart worm. He only had 1. He wss treated with a steroid to help his symptoms over the course of a few years the symptoms went which in turn meant the worm had died. He lived a further 3 years before renal failure took him. So heartworm in cats have been around for a long time but is not commonly known. All my cats r treated with revolution now.
Joan - Comment
Joan16 Jan 2014Reply
Now that I have found Pet Bucket, where Revolution is at an affordable price, I use only Revolution on all my pets. I used to use Revolution, but after retirement I could no longer afford it. I had such problems with Advantage and Frontline that I went searching the internet. Thank goodness I finally found Pet Bucket!!
Jose Crespo - Comment
Jose Crespo16 Jan 2014Reply
I beleive that finally found what is happening with one of my cat, my question is, only a blood test could dignose heartworm?
Serge - Comment
Serge17 Jan 2014Reply
I have cats, what is important is to always treat them against flees, because when a cat lick himself as his or her hygiene routine, he or she will swallow some flees, then inside the they become worms, so a regular flee treatment and a worm treatment once in a while is important too.
JosiesMom - Comment
JosiesMom18 Jan 2014Reply
@Jose Crespo: The usual test done to detect heartworm only tests for secretions from female heartworms. So if your pet is infected by a male heartworm the test will return a negative reading even though the make worm is present. If you treat for heartworm and kill the worm, your pet is put at serious risk of the worm bodies creating a life threatening blockage. It is really best to just begin a preventative plan when the kittens are very young.

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