Hi, QT, not to nitpick, but classic line breeding is widely used when breeding Arab horses - junior world champion from a few years back was the result of a Father /Daughter mating, done by a firend of mine. And of course, those of us steeped in equine lore know that todays Thoroughbreds all descend from 3 Arabian stallions - The Godolphin Arabian, The Byerley Turk and the Darley Arabian (Pony Club quiz sessions remain with you for decades:))
Gwen

When we had pedigree sheep we always line bred, but we knew our lines very well indeed, and had some excellent results.

Miss my sheep now.

Jo and the Casblaidd Flatcoats

If I remember correctly QT is in US like me. Things are somewhat different here regarding breeding. We often have many choices as to what lines we are going to use.

Carissa