Join Date: Apr 2013
Location: Southern Indiana
Thoroughbred is an approved outcrossing for quarter horses and it'd be rare to find a qh that didn't have some tb somewhere because they also played a big part in developing the breed.
I'm not sure when they started the appendix thing (1/2 qh, 1/2 tb) but an appendix can earn full qh status after gaining a certain amount of show points. At least it was this way. Been a long time since I quit breeding and keeping up on all the rules.