The Foundation Quarter Horse refers to horses tracing to the American Quarter Horse breed's earliest bloodlines, specifically those with limited or no recent Thoroughbred appendix breeding that has influenced modern Quarter Horse type. The "Foundation" designation indicates pedigrees connecting to the breed's founding horses, particularly through bloodlines established before the American Quarter Horse Association began allowing significant Thoroughbred crosses.
Several organizations register and promote Foundation Quarter Horses, with the Foundation Quarter Horse Registry being the primary dedicated registry. These organizations typically require pedigrees demonstrating high percentages of foundation bloodlines, often 85% or higher, with minimal Thoroughbred influence from appendix breeding. The American Quarter Horse Association also registers these horses, though without distinction from modern-type horses.
The term "bulldog" Quarter Horse historically described the compact, heavily muscled type that Foundation Quarter Horses preserve. This descriptor referenced their low, wide stance and substantial muscling compared to the taller, leaner horses developed for racing and certain show classes. Modern Foundation enthusiasts seek to maintain this original, functionally bred type.
Like all domestic horses, Foundation Quarter Horses carry the scientific classification Equus ferus caballus. They represent a preservation effort within the broader Quarter Horse breed rather than a separate breed, maintaining characteristics that defined the breed before intensive selection for specialized disciplines altered population type in the late 20th century.
