The Half-Arabian is not a distinct breed but rather a recognized designation for horses with documented Arabian ancestry comprising at least 50% of their genetic heritage. The term "partbred Arabian" is used internationally, while "Half-Arabian" remains the common American designation. The Arabian Horse Association (AHA) maintains separate registries for Half-Arabians and Anglo-Arabians (Arabian-Thoroughbred crosses), which merged with the International Arabian Horse Association in 2003.
To qualify for AHA Half-Arabian registration, a horse must have one parent registered as a purebred Arabian with the AHA or Canadian Arabian Horse Registry. The other parent may be a purebred of any other breed, a registered Half-Arabian, or even a grade horse with unknown breeding. This flexibility allows breeders to create custom crosses combining Arabian qualities with characteristics from virtually any other breed.
Anglo-Arabians represent a distinct category within the part-Arabian designation. These Arabian-Thoroughbred crosses must contain between 25% and 75% Arabian blood, achieved through various crossing combinations. Those exceeding 75% Arabian blood are registered as Half-Arabians rather than Anglo-Arabians. The Anglo-Arabian developed particular prominence in France, where the cross produced exceptional cavalry mounts and later sport horses.
Several popular Half-Arabian crosses have developed enough following to establish their own registries. The Quarab (Quarter Horse-Arabian cross) is registered through the American Half Quarter Horse Registry, while the National Show Horse (Arabian-Saddlebred cross) maintains its own studbook. The Welara (Welsh Pony-Arabian cross) and Pintabian (tobiano-colored Arabian) similarly developed dedicated registries while remaining eligible for Half-Arabian registration if requirements are met. Current AHA registration numbers exceed 357,000 Half-Arabians and 10,000 Anglo-Arabians.
