Heartworm Disease in Cats

Heartworm disease is caused by a large (8-12 inches long!) worm, carried by mosquitoes, which injects the larval stage of the parasite into the cat or dog. The larvae migrate through the body and eventually live in the heart, where they can cause extensive damage or death. Heartworms are less common in cats than in dogs, but the incidence seems to be increasing. Because there was no specific test for this disease until recently, and even now blood testing is not very accurate in cats, it is thought that heartworm disease is much more prevalent in the cat population than was previously believed.

Affected cats usually have only a few of these worms in their heart, but because the cat's heart is very small and the worms are quite large, even 1 or 2 worms can be fatal. Signs of heartworm disease in cats include chronic coughing, wheezing or vomiting and sudden collapse or death. The disease has usually been diagnosed after death with a necropsy (animal autopsy) because there was no blood test for heartworm disease in cats. There is still no effective treatment for cats that have heartworm disease but there is now a blood test to detect these parasites in cats, and a new once a month preventative medication.

Outdoor cats are most at risk, but interestingly enough a new study of feline heartworm disease in Texas and South Carolina showed that 36% of infected cats were kept totally indoors. Since it takes so few of the heartworm parasites to cause disease in cats, even the occasional mosquito finding its way into the home can carry more than enough heartworm larvae to be fatal.

Luckily, cats can now be put on the once a month preventative medication during the mosquito season, just like dogs have been taking for years. Though effective preventative medications have been available for dogs for many years, nationwide more than 1/3 of dogs are not being protected. Many of them are harboring the heartworm parasite. Mosquitoes then carry the disease from infected dogs to other pets, and occasionally to people as well. Wildlife, especially coyotes, wolves and foxes, can also spread this disease.

Heartgard© for cats is a chewable, good tasting tablet your cat should like. The price is quite reasonable, and the medication also helps prevent roundworms and hookworms - common intestinal parasites - as well. There is also a new preventative on the market called Revolution. This is an ointment you apply to the skin on the back of your kitten’s neck (where he can’t lick it off). Revolution prevents not only heartworm disease but also fleas, ear mites and several other parasites.