Dag-- if the "hmm" was directed at me, sorry for being a bit inflammatory.

I just get het up about this. So many millions of cats and dogs put to sleep every year and people still can't just get their damn pets fixed because "it's too mean!" ...it's somehow *not* mean to add to the number of animals getting put down, I suppose...it just burns me up. Sorry if I offended you, though.
Mushy (or flushy, as I said I was going to call you!

), only problem with that is how
determined cats get to escape from the house when they're in heat...Female cats turn VERY weird when they get in heat!! (It's quite unpleasant to be around, also) --I've had more than one friend with an exclusively indoor cat who had the same idea you do, but had no idea how fixated the cat would get on getting out, and the cats always managed it in the end. Got a friend with a litter right now, actually, that happened that way...