Kirsten - my kittens were dewormed as kittens. They had a fecal done several months later which still showed worms so they were rewormed and several weeks later they were clear. Now, they only require a fecal exam once a year to check for the presence of eggs. (there have been no more) If any are seen they will need treatment of course but the fecal would have to show worms first. I have never heard of routine worming of indoor kitties!! It is a pretty nasty drug so why would it be done unless worms were present?? Checking is very easy to do so why deworm unnecessarily??
Outdoor kitties - I have no idea...