Many vets prefer to give the antibody and antigen tests, as a positive test result show that the cat has been exposed and therefore should have the preventive treatment, even if the cat is not actually infected with the heartworms. Amazingly, some cats appear to be able to mount their own antibody response to their heartworm problems, and actually rid themselves of the condition without medical intervention. It is important to know that the diagnostic tests that have always worked well in dogs are not nearly as accurate in cats, based upon the different responses of the worms in cats noted above. There is a new antibody test on the market now, called Heska Feline Heartworm Reference Lab Diagnostic Test, which can detect even a single male heartworm, as it is sensitive enough to detect a single-sex worm infection, or infections with very small numbers of adult and immature heartworms. Heartworms are notorious for their ability to hide and thus be difficult to detect in cats.
Prevention is the best way to keep heartworms away from cats.
Heartgard can be given alone or mixed with food, and comes in two formulas, based upon the cat's body weight. Many veterinarians now agree that it makes sense to put all cats in a heartworm-endemic area on the preventive medication, which works by killing the heartworm larvae. It does not kill adult heartworms already in cats, but will keep cats from becoming reinfected. Killing the adult heartworms already in cats does not appear to be the best solution, as when a worm dies and begins to deteriorate, small pieces of it can clog the arteries and cause the death of the cat. Also, when a worm is inside a cat, it secretes a substance that prevents the cat's own immune system from reacting negatively to it.