There is a breeder of Labradors here in Norfolk who has THREE times passed dogs onto the RSPCA - they are not cruelty cases, just puppies she cannot sell, yet the council licence her and she keeps on breeding more. Each time the number given up has been in the region of 180 - 200!!!!!!
When they get to a certain age and they cannot be sold as baby puppies, she just moves them on and breeds some more.
The RSPCA are on a good little earner. Every time it happens they have a publicity drive and hundreds of people want to adopt them, at a cost of around �200 each, and they also manage to get their other dogs rehomed through the extra interest it generates.
Most breeders I know would take dogs back however old they were, or at least help with rehoming. Some do run on dogs to show, and then rehome them if they don't turn out to be suitable, or if they are kennel dogs and retire from showing they will let them go to live out their lives in a bit more comfort as a pet. However, this is not the same as dumping your dogs on a rescue just because you cannot sell them or breed from them any more, which is what puppy farmers often do. Yet another reason not to buy without doing your homework about the breeder.