The Heartlines Ranch philosophy is that large hearts enhance athletic & recuperative ability in all animals, whether equine or canine. When Secretariat died in 1989, the post-mortem exam estimated his heart weight 22 pounds, whereas the average thoroughbred's heart weighs about 8 pounds. Marianna Haun, author of the X-Factor books, took the assignment at Thoroughbred Times to investigate the implications of such a large heart; the search began for its' genetic origin, data was gathered from around the world by Marianna & her equine cardiologist partner, Dr. Fred Fregin. Many recent advances have come at Heartlines Ranch. All of our purchasing & breeding has been carried out to produce large-hearted foals, with a desirable genetic profile, at a reasonable cost.