I have a few stray / Feral cats in my area and I have decided to undertake getting them spayed, we trapped two today and they have had their surgery around 4 pm how long should I keep them contained before it is safe to release them back into the wild? I have 4 more trapped and ready to go to the Vet in the morning so I just want to make sure that I am doing this right and the cats will not get hurt. I had to release one already as she had just had a litter of kittens and I could not find them so I had to let her go so that she could go back to her kittens although I tried to follow her I still could not find her Kittens.