'Tis the Heartworm Season -- for Your Cat
Although we normally associate heartworm disease with dogs,
cats can and do get heartworms. If you live in an area where
there are mosquitoes and a population of dogs with heartworm
disease -- like the Southeastern United States, along the
Mississippi River and its tributaries, and certain areas of
Australia and Japan, for example -- your cat is at risk for
contracting heartworm disease.
Heartworm disease is the situation where adult worms (of the
species Dirofilaria immitis) have lodged themselves inside the
right chambers of the cat's (or dog's) heart. Sometimes the
heartworms will be in the large vein that feeds blood into the
heart, or occasionally in other parts of the body. A dog can have
tens, or even hundreds, of heartworms. Cats normally only have a
few, but even one heartworm can be deadly to a cat.
Heartworms can grow to be 4 to 6 inches long, and are skinny and
white. They start life, however, as larvae -- tiny creatures that
can swim in the bloodstream. The larvae go through several stages
before they mature into adult worms. One of these stages must be
passed inside of a mosquito in order for the maturation process
to complete.
Dogs are normally the host population for heartworm infection.
They are the animals in which heartworms live the longest and
produce the most larvae. This is because there are more
heartworms -- male and female -- inside of dogs, so the worms can
reproduce. Because there are so few heartworms inside of cats,
the chances of them reproducing and generating larvae is
extremely unlikely.
The spread of heartworm disease occurs like this. A dog that has
heartworms that have reproduced will have larvae in its
bloodstream for a period of time. If a mosquito bites the dog
during this time, the mosquito will pick up some of the larvae.
The larvae will pass through the next stage of their development
in the mosquito. At this point the mosquito can infect another
animal. If the mosquito bites a dog or a cat, the larvae get into
the animal's skin, continue to develop, and migrate to the
bloodstream, where they go to the heart and live as adult worms.
This animal now has heartworm disease.
The heartworms can cause allergic reactions, inflammation, and
fluid buildup in the lungs. Often, the most common symptoms in
cats are coughing and vomiting. Sometimes an infected cat shows
no symptoms at all. Unfortunately, the only sign may be sudden
death of a cat that appeared normal and healthy just a couple of
hours earlier. This severe reaction occurs when a worm dies. But
sometimes, the worm or worms will die inside the cat and the cat
will recover with no problems. It is impossible to tell in
advance how a given cat will react to a heartworm
infection.
Because one of the risks of heartworm disease is sudden death,
your veterinarian may recommend that your cat be placed on
preventative medicine. One such product is Heartgard for Cats
®. This is a pill that is given to the cat once a month
beginning one month before mosquito season and continuing until
one month after mosquito season. In mild areas, the cat may need
to be on preventative medication year-round.
If you have a dog that needs to go on heartworm prevention, you
will have noticed that the dog will first be tested for heartworm
infection. Cats are not tested beforehand because there are no
risks of starting preventative medication if heartworms are
already present. In addition, it is much more difficult to detect
heartworm infection in cats compared to dogs.
Note that the preventative medication is not a vaccine. It must
be given regularly during the time of the year that your
veterinarian indicates. When the cat takes the pill, the
medication kills any heartworm larvae in the cat's system,
preventing the larvae from developing into adult worms. Heartworm
disease cannot develop because there are no adult worms. However,
if the cat gets bitten again by a mosquito, any new larvae must
be killed; therefore, the medication must be given as long as
there is a danger of the cat being bitten by a mosquito. If your
cat is an indoor cat, don't think your pet is immune. About one
third of cats that contract heartworm disease are considered
indoor cats.
If you live in an area with a low rate of heartworm disease in
dogs, then your cat may not need to go on preventative
medication. But the best thing for you to do is discuss heartworm
disease and its prevention with your veterinarian. If you do live
in a high-risk area, you may save your cat's life with a simple
monthly regimen.
About the author:
Terri Hobbs is the webmaster for Crazy for Kitties where
you can find facts, articles, games, postcards, photos, and a
Kitty of the Week. Terri wishes to thank Dr. Susan Oltman, DVM,
of the Countryside Veterinary Clinic (410-461-0517) for her
helpful advice and information about heartworm disease.
Heartgard for Cats ® is a registered trademark of Merial Limited, Iselin, NJ.
Related Books from Amazon.com:
- The New Guide to Cat Care
- ASPCA Complete Cat Care Manual
- The Cornell Book of Cats: A Comprehensive and Authoritative Medical Reference for Every Cat and Kitten
