breeding registered horses

Question
I am currently breeding registered miniature horses.  I notice on many of the registration papers that many of the horses are related to each other...same horse used on both the dam and sire side.  What is acceptable in breeding horsese that are related?  How far back in the breeding do I need to go to check this when purchasing a new horse?  Thanks!

Answer
What you are talking about is line breeding which is the breeding of two aniamls who are distantly related to each other. They usually share a common ancestors but are not closely related. The main purpose of linebreeding is to transmit a large percentage of one outstanding ancestor's genes from generation to generation without causing an increase in the frequency of bad genes which can happen with inbreeding.

I find that it is best to go to at least the third generation when line breeding and to also make sure that you are not just line breeding on the sire's side but also the mares. Make sure that you are breeding the best to the best.

Lisa