HERDA-associated variant in bull-catching (vaquejada) Brazilian Northeastern bull-catching Quarter Horses

BACKGROUND: Bull-catching (vaquejada) accounting for approximately 13% of sport horses in Brazil. Genetic screening has enabled strategies to reduce the spread of inherited disorders, including Hereditary Equine Regional Dermal Asthenia (HERDA), a major skin disease included in the Six Panel required for registration by the Brazilian Quarter Horse Breeders Association. Although the HERDA-associated variant has been extensively studied in other disciplines, it had not been evaluated in Bull-catching Quarter Horses (QH). AIMS/OBJECTIVES: The present study aimed to determine the allele frequency of the pathogenic variant associated with HERDA in the Brazilian Northeastern bull-catching Quarter Horse population. METHODS: This study investigated the HERDA allele frequency in 141 Bull-catching QH from Northeastern Brazil using Sanger sequencing. RESULTS: Eight horses were heterozygous, resulting in an allele frequency of 0.028, the third highest among Brazilian QH disciplines. Assuming random mating, HERDA is expected to affect one foal per 1,000 births, with 58 carriers. CONCLUSION: Given nonrandom breeding practices, the actual impact may be higher, reinforcing the importance of mandatory genotyping to guide breeding decisions and reduce economic loss and animal suffering.