A study from Mississippi State University shows that most palomino show horses in America descend from six sires. In fact, one stallion accounts for nearly 60 percent of current bloodlines.

The researchers analyzed the pedigrees of 460 randomly selected horses that competed in the Palomino Horse Breeders Association (PHBA) World Show Championships from 2012 to 2022. They collected additional pedigree information from the online All-Breed Pedigree Database. The goal was to document “generation-to-generation inheritance patterns of the crème dilution allele, which is responsible for the palomino coat color,” explains Molly Nicodemus, PhD, of Mississippi State University.

The effort to better understand palomino inheritance patterns comes at a pivotal time for the PHBA. Founded in 1941, the registry for decades accepted only horses who passed strict inspection requirements. One such requirement was prior registration with the American Quarter Horse Association or other sanctioned organizations. In 2021, however, PHBA expanded eligibility to include unregistered palominos so long as they meet color requirements. In addition, under the new rules, photos of a prospective registrant can be submitted in lieu of in-person inspections.

Genetics of palomino coloration

“With non-registered horses, it is difficult to verify bloodlines, and photos can misrepresent coloration,” says Nicodemus. The genetics of palomino coloration can be complex, she adds. The responsible gene (allele) also produces several other colors, including buckskin, smoky black, cremello, perlino, or dunalino. “The crème allele dilutes the base coat of a sorrel/chestnut to give the palomino coloring,” says Nicodemus, who owns and shows palominos herself. “If, however, the base coat was a bay, then the offspring with the crème allele is a buckskin. If the base coat is sorrel/chestnut and the horse is homozygous for the crème allele, then the horse will be a cremello. A homozygous crème allele for a bay base coat creates a perlino. Verifying color based on photos can introduce potential issues for an association centered around a body color coming from the crème allele.”

Comparing pedigrees to PHBA registration records revealed some discrepancies, says Nicodemus. “We found several examples of mislabeled coloration—identifiable because the designated colors of a horse’s ancestors would not result in the color recorded on their registration papers.” Others had no color designation, she adds.

“Luckily, there is enough research now within equine color genetics that we can predict colors by using pedigree tracing,” Nicodemus says. “Thus, using general knowledge within equine color genetics, it is clear that there were potential mistakes within pedigrees on color designation, suggesting the value of genetic testing. The champagne allele, for example, has been a fairly recent finding.”

Six foundation sires

Over the course of their analysis, the Mississippi researchers identified six foundation sires for the modern stock-type horses registered with the PHBA. “The majority—58 percent—of PHBA horses trace back to a sire named Old Fred,” says Nicodemus.

Old Fred, a palomino Quarter Horse foaled in 1894. He became famous for producing running Quarter Horses as well as ranch horses. “While Old Fred’s prevalence of the crème allele within his offspring was desirable, his offspring were also known to be athletic. His consistency both in coat and structural phenotypical characteristics was desirable for breeders.”

The second largest percentage of pedigrees (16 percent) traced back to a stallion named Yellow Wolf. The third largest (9 percent) descended from Waggoners Rainy Day, and 5 percent were descendants of Hollywood Gold. All three of these Quarter Horse stallions had coat colors resulting from the crème allele. The final two foundation sires identified in the study were Yellow Jacket (4 percent) and Cotton Eyed Joe (3 percent).

The researchers conclude that “as the PHBA continues to grow, additional genetic testing to accurately identify the crème allele within the horses registered may further support the goals of a color registry based upon horses with a crème dilution allele-influenced coat color.”

Reference: “Pedigree tracing to determine the origins of the modern Palomino Horse Breeders of America stock-type horse,” Journal of Equine Veterinary Science, October 2024

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