Arthritis
Atopy (Inhalant Allergy)
Bufo Toad Poisoning
Cat Home Safety Tips
Collar Hazards
Common Things to Watch for
Dental Disease in Pets
Diabetes
Dog Safety Tips
Feline Heartworm Disease
Mallassezia (yeast) Dermatitis
Reasons to Neuter
Noise Phobia in Dogs
Weight Problems in Pets
Otitis (Ear Infections)
Parvo Virus
Pruritis (Itchiness)
Rabies
Seizures and Epilepsy
Senior Pets
Reasons to Spay
Toxoplasmosis, Cats and Women
...It's Pop-Quiz Time!!!
Okay, dog owners, by a show of hands, how many of you give your dog a
heartworm preventative? All right, let me count 1,2,3…. Ahh, just what I
thought a good many of you do.
Okay, cat owners it’s your turn, so let’s see those hands, how many of you
give your cat a monthly heartworm preventative? And yes, you owners of
"indoor only" cats have to answer too. Okay, let me count….hmm, just what
I thought, dog owners have the cat owners way outnumbered.
This is unfortunate because not only are cats susceptible to HW disease they
frequently have more severe clinical signs than dogs or they may die
suddenly without any warning at all.
What are heartworms? "Dirofilaria immitis" is a parasite that lives in and
damages the heart and pulmonary (lung) blood vessels. The worm is
transmitted from animal to animal by mosquitoes. Its life cycle is fairly
simple. Male and female worms living in the heart of a dog mate and the
female worm produces heartworm babies called microfilaria that circulate in
the bloodstream. When a mosquito feeds on the infected dog it sucks up
some of the microfilaria, which migrate to the mosquito’s salivary glands and
molt into infective larvae. The infective larvae are injected into a healthy dog
or cat at subsequent feedings and continue to mature over the next several
months in the animal’s tissues. They eventually migrate to the heart via the
venous circulation. Once in the heart, the larvae mature into adult worms.
Although caused by the same parasite, HW disease in cats does vary
somewhat than in dogs. Since cats are not the definitive host of the parasite
they are more resistant to the disease than dogs. If infected by a mosquito
the chances of a larva developing into an adult heartworm are lower in cats
than in dogs. But, if a cat does develop adult heartworms they can suffer
more serious or fatal reactions.
The symptoms of HW disease in cats are highly variable. Some cats may
show no signs of illness while others may die suddenly from a pulmonary
thromboembolism with or without showing any signs of dyspnea (labored
breathing).
Other cats may develop chronic HW disease and show non-specific signs
such as coughing, dyspnea, open-mouth breathing or recurrent vomiting.
Other signs may include decreased appetite, weight loss and lethargy. Any
cat showing these signs should be tested for HW exposure as soon as
possible.
Diagnosis of HW disease is more difficult in cats than in dogs. The typical
HW tests used in dogs detect either antigens from female worms or
microfilariae circulating in the blood. A positive test means that the dog has
heartworms.
These tests are less reliable in cats because cats rarely have circulating
microfilariae and the antigen tests do not work well in animals with low
worm burdens or immature or single sex (all male) worm infections which
are common scenarios in cats. If positive, the tests would indicate adult
worms in the heart, but a negative result does not rule out adult worms in
the heart.
A HW antibody test has been developed for use in cats. But a positive result
only means that the cat has been exposed to infective larvae from mosquito
bites. It does not mean that the cat has adult worms in its heart.
Unfortunately, there really isn’t a good blood test to determine if a cat has
adult heartworms.
Other tests that may be useful in diagnosing HW disease in cats include
"X-rays" of the chest that may show changes in the lungs or an ultrasound
exam that may show the worms in the heart.
Another major difference between cats and dogs is that while there is a
relatively safe and effective treatment for HW disease in dogs, none exists for
cats. Drugs approved for use in the dog have a high risk of causing serious or
fatal complications in the cat.
So what is a cat owner to do? Given the fact that cats are susceptible to HW
infection that may result in sudden death or chronic illness and the fact that
there is no safe treatment available for HW disease in cats many veterinarians
are recommending a monthly HW prevention just like dogs get.
There are several products approved for use in cats. The one I recommend
most often is "Revolution" [R]. It is a convenient, once a month topical
solution applied to the cat’s neck and tested 100% effective in preventing HW
disease. This medicine also kills fleas and controls other parasites such as
ear mites, hookworms and roundworms.
For more information on feline HW disease visit these websites:
www.heartwormsociety.org/FelineHeartwormInfo.htm
www.revolutionpet.com.