well, right now the only real solution is probably euthanization, but I don't believe they should be shooting them. The shelters are probably already overun with cats who are being euthanized because nobody wants them, so as much as I hate to say it, there is no good solution to this problem. However, to stop this type of thing from happening, spaying and neuturing are really the only solutions, but I am against the idea of having to say that we are "breeders" is we keep unaltered pets. I myself have 10 animals and all are fixed except for my 4 guinea pigs and my two oldest male dogs who are brothers. My male dogs are not breed and they have never seen a female dog in their life (besides my little terrier, who is spayed). I am not a breeder and I just didn't know any better, however, I would still not neuter them to keep them from breeding, because I do not breed. I would neuter them because one of my dog's has a terminal illness that is a direct consequence of him still being intact.
I have taken in stray cats all of my life and I am very pro-animal welfare and would be extremely upset if I were labelled a breeder, because this has already been done to me by the local SPCA. I wanted to foster homeless cats, but they said that "responsible" owners get their animals spayed/neutured, which I do agree with however, if situation is different. My dogs are now to old to neuter (11 years), so I will not be able to provide a temporary home for homeless cats until they pass away, which is such a morbid thought. So, basically I do agree 100% with spaying and neuturing, but just because someone doesn't do it doesn't mean that they are a breeder or an irresponsible owner.