The other thing we do in the horse world (and this just occurred to me) is that we do not generally speaking deselect a horse because of a single fault. Have a mare with a long back? Breed to a shorter backed animal. Have a mare with an ugly head? Breed to pretty heads etc. etc. This article is an example of the guidance that people are given: https://thehorse.com/132564/breeding...ecting-a-sire/
Obviously, it's a different world, and a horse is going to have one foal and not 5+ per breeding, but it sure is curious.
And then many of the equine breeds allow outside blood in, from the quarter horses allowing TB blood in, to the warmblood inspections which are purely about type.
We treat dogs very differently, and I'm not entirely sure why.