Summary: Background: Brain natriuretic peptide (BNP) serves as a crucial cardiac biomarker in human and small animal veterinary medicine, yet its role in equine cardiology remains underexplored. Objectives: This study aimed to investigate the influence of different exercise types on BNP concentrations and single brief echocardiographic parameters in two distinct horse populations, while also examining potential correlations between BNP concentrations and echocardiographic variables. Study design: Forty clinically healthy horses, categorised into working and sports groups, underwent exercise testing exercise to their purposes. BNP concentrations were measured using a horse‐specific ELISA kit, and brief echocardiographic examinations were conducted 24 h post‐exercise. Methods: Blood samples were collected before, after exercises, and at rest to determine plasma BNP concentrations. The brief echocardiographic examinations looked only at M‐mode imaging from the right parasternal window, and assessed cardiac chambers and ventricular diameters. BNP concentrations and echocardiographic variables were compared between the two groups. Results: Exercise did not significantly increase BNP concentrations in either group, with sports horses exhibiting higher basal BNP values (18.0–1973.0 pg/mL) compared to work horses (14.4–1074.5 pg/mL). No significant differences in BNP concentrations were observed between breeds, sexes, or pregnancy statuses. Brief echocardiographic examinations using M‐mode imaging from the right parasternal window revealed significant differences in right ventricular dimensions in diastole and relative wall thickness between the groups. A low negative correlation ( r = −0.329, p = 0.038) was observed between BNP concentration and fractional shortening. Main limitations: Single pre‐exercise blood sampling, brief M‐mode echocardiography, and lack of exercise standardisation in the endurance horse group limited assessing high biological variability on BNP concentration and echocardiographic parameters in the tested horses. Conclusions: Assessing BNP concentrations and echocardiographic parameters during different exercises can be helpful in examining the functional status of the equine cardiovascular system, guiding tailored exercise regimens for optimal equine well‐being.

In the present study modern technology of DNA extraction and automatic genotyping was applied in Bosnian and Herzegovinian autochthonous horse breed by using 17-Plex horse genotyping kit. The study was aimed at investigating usefulness of the 17-plex STR Kit for Bosnian mountain horse genotyping and establishing highly useful microsatellite markers system for genetic diversity studies in Bosnian mountain horse breed. Genomic DNA was extracted from whole blood collected from 22 unrelated Bosnian mountain horse specimens. A total of 95 alleles were detected. Average number of detected alleles per locus was 5.588, varying from 3 (HTG7) to 10 (ASB17). Average effective number of alleles was 3.603, fluctuating from 1.789 (HMS7) to 5.728 (HMS2). The observed heterozygosity ranged from 0.136 (HMS3) to 0.909 (ASB2) with a mean of 0.631. The results indicate that the studied population originates from the appropriate number of parent generations. The mean expected heterozygosity was 0.690, varying from 0.441 (HMS7) to 0.853 (ASB17) indicating high genetic variability within Bosnian mountain horse population. The PIC values ranged from 0.409 (HMS7) to 0.837 (ASB17) with a mean of 0.643, suggesting that 94.12% markers were quite informative in terms of their suitability for genetic diversity studies .The most polymorphic locus was HMS2 and the least polymorphic locus was HMS7. The inbreeding coefficient ranged from -0.030 (HMS7) to 0.807 (HMS3) with a mean of 0.077. Inbreeding coefficient values indicated no shortage of heterozygotes in Bosnian mountain horses. Deviation from Hardy-Weinberg equilibrium (p<0,05) was found in three loci (HTG10, HMS3 and ASB17). The applied set of 17 microsatellite markers proved to be sufficiently specific for use in genotyping of Bosnian mountain horse. Considering the values of HO, HEand PIC over 0.6, five microsatellite markers system (HTG4, AHT4, AHT5, ASB2, HMS2) is considered to be highly useful for genetic diversity studies in Bosnian mountain horse breed.