In my breed there are some studs that have produced well over 300 puppies. That doesn't seem like a lot when most Jrts whelp an average of 5 pups per litter but that puts the number of breedings per year up alot. And if those studs (which some have) been very prolific in a undesirable genetic flaw like cataracts etc (which of course hasn't been discovered until its too late or its a matter of breed and don't tell), it can be so very difficult for get away from those lines. Let alone trying to get away when those lines have also been heavily linebred. I am watching one of my litters like a hawk right now (they are 3 1/2 yrs old ), because although at the time the dam was CERF clear, she went completely blind at a young age (6 1/2), so if any of those pups become effected that means that my stud is a carrier for the cataract gene. If they remain CERF clear, then that is a huge bonus for me and my lines. So now it's a wait and see while continuing to CERF everyone as usual.