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What Is an Appendix Horse?

| Updated September 26, 2017

An appendix horse is a cross between a registered quarter horse and a registered thoroughbred. This relates to first generation crosses, not later breedings between two appendix animals. The ideal result is a horse with the quarter horse's calmer disposition and the thoroughbred's athletic ability. While individuals vary, the appendix horse is generally larger than the typical quarter horse but less rangy than a thoroughbred. While more refined than the quarter horse, he's not as elegant as the thoroughbred in appearance.

Registering An Appendix Horse

The American Quarter Horse Association requires approval of the thoroughbred parent before you can submit an application for registering an appendix horse. You must include a photocopy of the Jockey Club certificate -- front and back -- proving that you own the horse in question. The Jockey Club is the governing body of thoroughbred horse registration. Send in four color photos of your thoroughbred, along with the required application fee. The AQHA also calls for a statement allowing it to seek DNA information from the Jockey Club, if necessary. If there is no DNA on file with the Jockey Club, you must pay a fee and have your horse tested before the AQHA considers approval.

Registration Certificate

When your foal is born, if the thoroughbred parent is already approved, you may apply for an appendix registration certificate. Once received, you can compete your appendix horse in AQHA-sanctioned events. The registration certificate received from the AQHA clearly indicates that the animal is an appendix, with a registration number beginning with X. If you decide to breed your horse to a registered quarter horse, the resulting foal is eligible for AQHA registration. That's not the case if you breed your horse to a thoroughbred or another appendix registrant.

The AQHA makes exceptions to this rule if the appendix horse has achieved certain accomplishments, either at AQHA horse shows or at official quarter horse racetracks. These include receiving an open division -- not youth or amateur -- Register of Merit at an AQHA show, or a speed index of at least 80 for a racehorse. Submit the proof of the horse's advancement to the AQHA, along with appropriate fees, and future offspring of either a stallion or mare can be registered as appendix horses even if the other parent was a thoroughbred or appendix.

American Appendix Horse Association Registration

The American Appendix Horse Association, which is not affiliated with the AQHA, allows appendix to appendix crosses, quarter horse/thoroughbred crosses and paint/thoroughbred crosses to qualify for AAHA registration. The AAHA's goal is to make the appendix a recognized breed.