Unfortunately, heartworms can cause a lot of damage before the pet shows any clinical signs. Several drugs prevent heartworm infection. Heartworm medication for cats has recently been approved. The drugs kill the immature form of the heartworm before it reaches the heart. These drugs must be administered monthly or daily, depending on the type prescribed, throughout mosquito season.
Veterinarians can recommend an appropriate drug regimen depending on area.
If the pet is found to have heartworms, treatment to eliminate the adult form is available, but it is very difficult and can be quite harsh on the pet. A separate treatment a month later is necessary to remove any microfilaria that may be present in the pet's circulatory system. Treatment in the cat is even more difficult. Surgical removal of the heartworms may be necessary. As with most diseases, heartworm is much easier to prevent than to treat.