The Genetic Basis of Piebald Coat Colour in Hucul Horses in the Context of White Markings and Crypto-Tobiano as a Breeding Problem in Poland

The aim of the study was to analyse the genetic basis of piebald coat colour in Hucul horses and to verify their coat colour in breeding records. Tests were performed with DNA purified from the whole blood samples of 242 Hucul horses with different coat colour patterns. DNA was analysed to identify an inversion in ECA3 (PCR). The results confirmed that the inversion on ECA3 is a direct factor determining piebald (tobiano) colour in the analysed Hucul horses. No inversion was observed in any of the solid coloured horses, but it was present in all the piebald ones. It was also identified in 18% (11 of 61) of the horses from the group of horses qualified in the passport as solid coloured with white markings. In fact, these horses had the tobiano gene that is phenotypically identifiable as crypto-tobiano, which may give the false impression of having white markings and lead to error when describing a horse. This is an important issue, in particular with regard to the breed standard, which eliminates Hucul horses with white markings from breeding.