Q: My cat Daisy Mae recently tested positive for feline heartworms. I understand that a positive test doesn't mean she has worms, only that she's been exposed to them. Now I have to recheck her blood to make sure she doesn't actually have the parasites. The worst part is, I recently learned that feline heartworm disease can be prevented. Could you address this issue so that more people in heartworm-prone areas keep their cats protected?

A: You're right. Feline heartworm disease is nearly 100 percent preventable. We have the means; unfortunately, we too often fail to use it.

Here's some background:

Mosquitoes can pass along the larval form of heartworms to dogs and cats. In canines, the worms mature in the bloodstream and lodge in the heart. In felines, however, the larval forms can cause problems all by themselves. When allowed to grow they lodge, not in the heart, but in the sensitive tissues of the lungs. This leads to chronic lung disease (like asthma), vomiting, sluggishness, even sudden death.

In short, heartworm disease is typically more deadly for cats than for dogs. Though their immune system should be capable of clearing the larval forms, it doesn't always. And when it doesn't, feline bodies are just not set up to handle these invaders like better-adapted canine bodies do.

To make matters worse, killing the heartworms as we do for dogs is not doable in cats. The treatment would kill a cat outright. Instead, they have to be treated symptomatically for their disease. Though new research suggests that 50 percent of cats clear the infection within four years, living with a potential time bomb is a terrible thing.

That's why many veterinarians recommend preventing heartworm infection with parasite killers that target the baby forms. This is considered safe and effective.

Oral products (like Heartgard and Interceptor) are available as monthly chewables. Topical forms (like Revolution and Advantage-Multi) also do nice work. I especially like these latter products as they do double duty for fleas and other parasites.

Some veterinarians say indoor cats don't need such protection because their incidence of heartworm is very low. The truth is we don't really know, so I believe it never hurts to be safe -- not when the alternative could be deadly.