I wormed our cat 6 weeks ago (try to do it monthly but often it'll end up being two months rather than one) - well, I just stepped into a dried-up puddle of vomit with lots of roundworms in it . I tracked down the cat immediately and shoved another Drontal tablet down his neck (after binning the - thankfully cheap - rug he'd chucked up on).
He is a hunter, which is good and I would not stop him from catching things... Should I be more conscientous about worming monthly? I am surprised that he managed to develop a full-blown roundworm infestation in such a short amount of time though, I'm quite certain that he didn't spit out the tablet