Feline Heartworm, yes cats can get heartworm as well as dogs. The typical cat with heartworm will have periodic bouts of coughing, which is often diagnosed as Feline Asthma.
There are blood tests for this condition, but they can give a false negative result. If the test is positive it means that the cat has or had an immature or adult heartworm living in the blood vessels of the lung . Unfortunately a negative test does not mean that the cat is free of the worms, and so it is difficult to be completely sure that the cough is not caused by heartworm. Sometimes it can be diagnosed by X ray or Ultrasound tests.
At this time there are no treatments for heartworm in cats as there are in dogs, but there are preventatives that will protect your cat from contracting heartworm.
The preventatives should be given monthly from March / April until November / December, in the Long Island area. There are currently three preventatives approved for cats (Interceptor, Feline Heartguard and Revolution). Just released this Spring '07 in the US is a new product Advantage Multi, which controls Heartworm, Fleas and most bowel worms, and also Ear Mites.
Testing is not necessary, but is recommended, before starting preventatives, as the test can give false negative results. If the cat has Heartworm and receives preventatives, it would do no harm as the preventatives only affect the very early (Immature) stages of the worm. However more routine testing may alert owners to the presence of this parasite and some measures may be taken to be aware of the possible consequences.
Long term affects of Heartworm can include coughing or shortness of breath which can be intermittent or continuous, and more serious shock like reactions. The shock like reaction can occur very suddenly and result in death. Other signs that are seen include frequent vomiting, fainting episodes, and central nervous system signs (Seizures).
Indoor cats are not protected just by being indoors. A recent study found that approximately one third of cats that were confirmed as having Heartworm were strictly indoor cats. So the moral of this story is to get your cats on a Heartworm preventative, without it you may loose your cat to this growing problem.