Much to my annoyance my friend at works cat got pregnant "because she managed to escape" (I've managed to keep 3 cats indoors for 5 years now including Soap before she was spayed). Anyway said cat went on to have 3 kittens, my friend was able to home 2 but had one left (surprise surprise a little black female). After a few more escape attempts *sigh* my friend got her cat to the vets to be spayed and mentioned that they still had one kitten to be homed. The vets offer to rehome kittens as long as the mum cats are spayed by them. Kittens are kept in special rehoming pens in the surgery and are vaccinated, microchipped etc before going to their new homechecked homes. I personally saw this as a pretty responsible thing to do and of course it also helps out the already overburdened rescues.