Horse Tack Review


New Registration Rule Could Affect Certain Offspring Born in 2007

American Quarter Horse Association

As the breeding season enters its busiest time, owners and lessees of mares and stallions should be reminded of AQHA Rule 205(c)(3), which first appeared in the 2005 AQHA Official Handbook of Rules and Regulations. That rule concerns descendants of the stallion Impresssive.

Rule 205(c)(3) states: “Effective with foals born on or after January 1, 2007, all descendants of the stallion Impressive, AQHA registration number 0767246, shall be required to be parentage verified and HYPP tested, subject to the conditions in [Rule] 205(c)(2). Any foal testing homozygous positive for HYPP (H/H) will not be eligible for registration with AQHA.”

Hyperkalemic periodic paralysis – or HYPP – is a muscular disease caused by a hereditary genetic defect that leads to uncontrolled muscle twitching or profound muscle weakness, and in severe cases, may lead to collapse and/or death. According to research, HYPP exists only in certain descendants of Impressive. A fact sheet and other information concerning HYPP appears on AQHA’s Web site at

Members wanting to research pedigrees can visit the member services section of AQHA’s Web site and select the horse research option on the top navigation bar. Additionally, a copy of AQHA’s entire handbook is available in the member services section for those wishing to view any rule.