X-rays, monitoring, and bracing owners that this cat may go into a fatal crisis when this heartworm dies (they live about two years). There's not a whole lot you can do to prevent that. Despite the best of efforts, those cats die. Sometimes specialists can surgically/manually remove heartworm, but it’s costly. How often it's done, I'm not sure. It's probably a pretty risky procedure, too, I would think.

It can prevent it. I don't think the research has been done out there yet to see if chronic prevention eventually treats or kills the heartworm. Having an adult heartworm die is often fatal to the cat, so we can’t let anything reach adulthood by prevention.

If you miss a dose, keep going. As soon as you realize you've missed it, go ahead and give the cat another one and just go on their regular monthly routine. If they are not showing any symptoms, great, we don't go any further with that.

If a cat does get an adult heartworm or two, there is no treatment available. They can't get the conventional treatment that dogs do. The medication is somewhat toxic in a cat. Then as the worm dies, the cat often dies as well, which is why prevention is so vital. If infected, the cat develops chronic asthma-like symptoms once infected with heartworm, and that lasts for life. That's treated with things like corticosteroids and bronchodilators as needed, but there's permanent damage done to the lungs.

Preventing standing water is essential. You can use area mosquito sprays and things like that, and they are safe if you follow directions. Anything you can do to keep the mosquito population down in the area helps. Usually, that is combated by avoiding standing water in those areas, dumping standing water from your flower pots, and other things like that.

There are not. Vector and mosquito control can help, but still, those preventative products are essential. A lot of those preventative products also keep fleas and ticks away and help treat intestinal parasites.