It's to easy to make a blanket statement like that... I have always spayed and neutered because I'm not a breeder and I have always rescued. BUT I also have a Leonberger. You will never, ever find a Leonberger in a Shelter. It's a breed that almost went extinct after being used to pull ammo carts in WW2. Would be sad to have a world with no Leonberger's, they are the best family dog you can find and decent at protecting the flock too.