 Throughout the years, closely breeding back, or inbreeding, to the lines of Poco Bueno increased the frequency of homozygousity in the population, thus increasing the number of affected animals.The 2004 Quarter Horse News Stallion Register revealed that of the top 100 cutting horse stallions, 14 are known HERDA carriers.Today, approximately 28% of all horses of cutting horse bloodlines are carriers of HERDA.