Abstract
INTRODUCTION: The Silesian horse is a heavy warmblood breed developed in Polish Silesia through the covering of local mares by East Frisian and Oldenburg stallions. Because of its historical significance and genetic heritage, the breed is part of a conservation programme in Poland. One of the genetic disorders of concern in warmblood horses is fragile foal syndrome (FFS), an autosomal recessive disease caused by a mutation in the PLOD1 gene (c.2032G>A). Affected foals either perish in late pregnancy or are born with severe connective tissue abnormalities, leading to early death. As carriers do not exhibit symptoms, genetic testing is crucial for responsible breeding. This study aimed to assess the prevalence of the PLOD1 mutation in the Silesian horse population. MATERIAL AND METHODS: Samples of DNA from 284 breeding horses were analysed using PCR and restriction-fragment length polymorphism and validated by Sanger sequencing. RESULTS: The detected carrier frequency was 14.6%, an increase over previously reported carriage for this breed. Compared to other warmblood breeds, the carrier frequency in Silesian horses was higher than in Swedish Warmbloods, similar to the frequency in Hanoverians (14%) and also aligned with that in Oldenburg horses, from which Silesians historically derive. CONCLUSION: The results highlight the need for continued genetic monitoring and informed breeding strategies to prevent the spread of FFS in the Silesian horse population.