Some people will just never learn. There should be a law saying that all dogs have to be spayed or neutered, unless you have a license to breed them. You shouldn't be able to license your pet unless it's sterilized, then if you're caught with a pet without a license the fine should be much higher than the price of the surgery.

Do any states already have laws like that? If not I don't know why - it would help the problem so much.