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Heartworm Disease

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Heartworm Disease in Cats

When it comes to heartworm disease, dogs and cats have a lot in common.
But new research shows that in cats there is the potential for more severe
reactions and even sudden death. Indoor cats are also at risk for heartworm

Cases of heartworm disease in cats have been reported across the United
States and many other countries. Heartworm disease is most common in
areas where dogs are also at risk.

What are the signs?

The most common signs of heartworm disease in cats

coughing , vomiting, breathing difficulties, weight loss, and lethargy -
are often mistaken for other conditions such as asthma, pneumonia
and digestive problems. In fact, most common clinical signs of
heartworm disease in cats resembles bronchial asthma.


Once a cat is diagnosed with heartworm disease, managing the disease can
be difficult. Treatment, as well as non-treatment, is very risky, because
there's currently no approved product for treating adult heartworms, and
the onset of clinical signs is impossible to predict in cats that are left
untreated. Even if the disease is treated, your cat may experience severe
complications or even death when the worms die. Prevention is the best
medicine. Ask your veterinarian about heartworm disease prevention for
your cat. It will help give your feline friend the best chance for a long and
healthy life.

Heartworm Disease FAQs

What is heartworm disease in cats?

Heartworm disease in cats is a serious and potentially fatal condition caused
by Dirofilaria immitis. This is the same parasite that causes heartworm
disease in dogs but new research shows a potential for more severe
reactions and even sudden death in cats.

How do cats get heartworm disease?

Cats get heartworm disease the same way dogs get it. Mosquitoes transmit
the disease by biting an infected animal, then passing the infection on to
other animals they bite.

Where are cats at risk for heartworm infection?

Cats are at risk wherever dogs are at risk, including cats that live indoors.
In fact, some studies estimate that 70% of cats may be at risk in areas
where there are heartworm-infected dogs.

What are the signs of heartworm disease in cats?

Common signs of infection are:

Breathing difficulty
Weight loss

Other more acute signs are:

Sudden death

These signs may also be seen with other feline diseases. Ask your
veterinarian about your cat's risk for heartworm disease.

How can heartworm disease be treated?

Currently there is no approved product for treatment of heartworm disease
in cats.

What can I do to prevent heartworm disease in my cat?

Prevention is your best option. Ask your veterinarian for more information.

Should my cat tested?

If you live in an area that is considered endemic for heartworms then your
cat is at risk for getting heartworms, if your veterinarian recommends that
your dog be tested then heartworms are probably a problem in your area.
Heartworm infection is endemic in Florida. However if you do not plan to
place your cat on heartworm preventative, then knowing whether or not
your cat has heartworms is academic, if the cat is not symptomatic.

If my cat has symptoms of heartworm disease, which test should be

Most veterinarians would recommend that a heartworm ANTIBODY test
be performed as the first diagnostic test. This will pick up about 75-85% of
cats with heartworms; however it will miss 15 - 25% of cats. if there is a
strong suspicion of heartworm infection and the heartworm test was
negative, another test (chest radiograph, echocardiogram, ANTIGEN test
or even another laboratory's ANTIBODY test) should be performed.

What should I do if heartworms are diagnosed?

In dogs, when heartworm infection is diagnosed, medication is given to kill
the adult heartworm to rid the dog of the infection. This medication has
been given to cats with some success however the likelihood of severe
reactions to death of the heartworms has prompted most veterinarians not
to use it in cats.

Most veterinarians will recommend that a course of coorticosteroids (like
prednisone) be given to reduce inflammation, this may help control
symptoms but not cure the disease. Some veterinarians in conjunction with
the corticosteroid also use a bronchodilator.

Unlike the dog. we usually "let the infection run its course" and hope that the
cat does not die suddenly from the disease before the worm dies naturally.
A few veterinary cardiologists have tried to remove the heartworms from
the right atrium. This has been successful in some cases (when the worms
are located in the right atrium) but the risk of complications at this time
probably outweighs the benefits.

Should I put my cat on heartworm preventative?

There are few reasons for NOT placing a cat on heartworm preventative.
Currently there is only one heartworm preventative marketed for cats
(HEARTGARDŽ for cats). The active ingredient in it is ivmneain (dose is
24 micrograms per kilogram once per month). As the product is currently
packaged (chewable flavored tablet), many cats do not find it palatable.
Since the tablet is so big, "pilling" the cat with it is not a good option.

As an alternative, some veterinarians have used the canine HeartgardŽ
product or milbemycin (lnterceptor~). The FDA licenses neither of these for
use in cats. The likelihood of reactions to ivermectin is small if the
appropriate product is used. The main obstacles are packaging and cost.

Can my dog get heartworms from my cat?

Theoretically yes your dog could get heartworms from your cat however
realistically this is not likely. Because the worm burden of most cats is small
(1-4 worms), the likelihood of being infected with a male and female worm
are small. Secondly, the offspring of the heartworms (the microfilaria) are
rarely found circulating in infected cats' blood.

So when a mosquito feeds, the likelihood that it would pick up the
microfilaria is small. It is more likely that mosquitoes that have fed on
neighborhood dogs that are infected would infect your dog.

My cat only lives indoors so it can't get heartworms, right?

Indoor cats are diagnosed with heartworm infections just as commonly as
outdoor cats. One study from South America showed that the mosquitoes
that prefer to feed on cats prefer to live indoors. This means that although
keeping the cat inside reduces feline leukemia virus or feline AIDS virus
infection, feline heartworm infection is not reduced.

Some cats would rather play with their food instead of eating it

If your kitty considers it's food boring, then perhaps you
would be wise to giving some consideration to giving
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Check out this Feline Cuisine that is so Healthy for your Cat

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