~9 million dogs/cats are killed every year simply because there are not enough homes for them. I would argue that if the said puppies/kittens were just going to go to the pound and get euthanized anyway, I'd much rather have them go to feed another animal (or even humans in dire straits) than get dumped in a landfill. At least then, their deaths serve a purpose.
This coming from a person who used to do foster/rescue work and LOVES cats and dogs alike.