Predisposition to Nasal Bleeding in Horses

The predisposition of horses to nasal bleeding significantly affects their performance and requires special control, particularly in the breeding work aimed at improving the breed and increasing its working abilities. One of the causes of such bleeding is spontaneous nucleotide substitutions in the D'-D3 domain of the von Willebrand factor. The presence and distribution of mutations in the D'-D3 domain of this factor (c.2826 A > C in exon 22, leading to the replacement of lysine by asparagine) in Russian horse breeds (Russian Trotter, Russian Saddle horse, Russian Heavyweight, Altai, and Karachai horse breeds) were analyzed. The highest frequency of this replacement was found in the Russian Trotter and Russian Heavyweight. We aimed to clarify the possible association of this mutation spread with the population and genetic relationship between horse breeds. The polylocus genotyping of 26 genomic DNA fragments flanked by inverted repeats sections of microsatellites (GA) 9 C, (AG) 9 C, and (GAG) 6 C (Inter Simple Sequence Repeats—ISSR-PCR markers) was performed, genetic distances were calculated, and corresponding dendrograms were constructed. It was found that the prevalence of the detected mutation is not related to the population and genetic proximity of the breeds. Historically, the Orlov horse breed had been involved in the breeding of the Russian Trotter and Russian Heavyweight. Therefore, it is possible that the high frequency of this mutation in the Russian Trotter and the Russian Heavyweight may be due to its presence in the Orlov horse breed that was the source for these breeds.