Pedigree tracing to determine the origins of the modern Palomino Horse Breeders of America stock-type horse

Registration numbers for the Palomino Horse Breeders of America (PHBA) have risen with the assistance of new registration guidelines. These changes in guidelines allowed for registration of any horse with a palomino body color, including those with unknown pedigrees. While this promoted registry growth, documenting the breed's orgins from those known pedigrees making up the breed's foundation is important with the introduction of unknown pedigrees. This can be accomplished using pedigree tracing, which is of particular value for color registries as the study of coat color patterns is plagued with misunderstandings due to pedigrees with inaccurate color designations. Thus, the objective of this study was to develop an understanding of the historical origins of the modern PHBA stock-type horse through pedigree tracing. Horses (n = 460) were randomly sampled from published entries from 10 years (2012-2022) of the PHBA World Show Championship Horse Show. The All-Breed Database was utilized to obtain documentation of extended pedigrees that included uninterrupted generation-to-generation inheritance patterns of a cream dilution allele-influenced coat color. Pedigrees were traced back to the earliest recorded relative. We observed six foundation sires contributed to the modern PHBA stock-type horse with the majority (58%) tracing back to a sire named Old Fred. Two identified sires, Yellow Jacket (4%) and Cotton Eyed Joe (3%), have conflicts concerning color designation. While these results assist in documenting the breed's origins, genetic testing is required to accurately identify the cream dilution allele within the horses registered to ensure a phenotype-based solely on the cream dilution allele.