BackgroundOxidative stress (OS) associated with an intense exercise may have a negative influence on equine health. The aim of this study was to determine the effects of endurance races on oxidative and antioxidative status of horses by evaluating changes in reactive oxygen metabolites (d-ROMs), malondialdehyde (MDA), biological antioxidant potential (BAP) and oxidative stress index (OSI) values. The study was carried out on 53 race starts (28 individual horses) competing at different endurance races according to distance (40 and 80 km) and difficulty (easy and demanding). Blood samples were taken before and after the race.ResultsCompared to levels of OS serum biomarkers before the race, an increase in values of d-ROMs (P <  0.01), MDA (P <  0.01), and BAP (P <  0.001), and a decrease in OSI (P <  0.001) have been noted after the race. Contrary to other measured biomarkers, BAP did not show significant individual effects of horses. Horses competing at shorter races have shown a significant change in d-ROMs (P = 0.002), BAP (P <  0.001) and OSI (P = 0.004), whereas those competing at longer races in MDA (P = 0.002), BAP (P <  0.001) and OSI (P <  0.001) post-race values. Endurance racing induced changes in values of d-ROMs, BAP and OSI during both easy and demanding races.ConclusionsChanges in all measured OS biomarkers indicate that prolonged aerobic exercise during endurance race could contribute to the imbalance between oxidants and antioxidants in horses, mainly characterised by a pronounced antioxidant response. Biological antioxidant potential was found to be the most reliable biomarker of OS in endurance horses in the present study.

During intensive physical activity horses are exposed to thermolysis, electrolyte loss and rising amounts of catabolic products, which results in alterations of biochemical blood parameters due to the horse’s adaptation to metabolic stress. The aim of the present study was to determine the effect of intensive physical activity on serum biochemical parameters in horses competing in 40 and 80 km endurance races. Blood samples were taken from 28 horses before and after the race over four competitions, with a total of 53 samples analyzed. Biochemical parameters studied included creatine kinase, lactate dehydrogenase, aspartate aminotransferase, urea, creatinine, gamma-glutamyl transferase, glucose, triglycerides, cholesterol, sodium, potassium, calcium and magnesium. The extent of change in pre- and post-race values was compared between categories of age, gender, breed, distance and average speed of horses. Creatine kinase and blood glucose values prior to the race were higher than the reference values. Values of renal parameters and parameters of muscle damage increased after the races, and the degree of change was more pronounced at longer racing lengths, as well as at lower average speed. Electrolyte loss was more prominent during longer races. This study demonstrated that endurance races cause evident changes in serum electrolyte concentrations, renal parameters and markers of muscle damage in horses. These changes are observable in horses at both short and long duration endurance races.

The composition of adipose tissue in brown bears (Ursus arctos) is highly variable and depends on an individual's feeding habits. Fatty acid composition of subcutaneous adipose tissue (SAT) may provide insight into brown bear feeding habits, for which data are scarce. The aim of this study was to determine the lipid composition of SAT and variations in the composition of fatty substances with regard to gender and to assess SAT relative to season and body mass (BM) of brown bears in Croatia. Seventy-six tissue samples of brown bear SAT were analyzed in this study. We found that gender, season, and BM significantly affected the lipid composition of SAT. Both females and males had higher percentages of saturated fatty acids and monounsaturated fatty acids (MUFAs) in SAT in spring than in autumn, while the percentage of polyunsaturated fatty acids (PUFAs) was higher in autumn. The prevalence of MUFAs in SAT and the greater presence of PUFAs in autumn, together with the presence of odd-chain saturated fatty acids, indicate the importance of these fatty acids in brown bear physiology. We suggest that the lipid content of adipose tissue may provide valuable information on changes in brown bear condition in response to feeding habits and the effects of supplemental feeding.

Sindrom iscrpljenosti konja (engl. exhausted horse syndrome, EHS) podrazumijeva multisistemski poremećaj u konja koji kroz duži vremenski period sudjeluju na natjecanjima, posebno pri toplijim vremenskim uvjetima. Zbog pretjeranog tjelesnog napora dolazi do dehidracije, hipovolemije, gubitka elektrolita, poremećaja acido-bazne ravnoteže, gubitka zaliha energije i hipertermije. Klinička slika ovisi o stupnju i brzini javljanja umora u konja te o toleranciji pojedinog konja na tjelesni napor. Dijagnoza se postavlja na temelju anamneze, kliničkih znakova i rezultata laboratorijskih pretraga. U težim se slučajevima dijagnoza lako postavlja, dok je rano prepoznavanje zbog blagih simptoma i nedostatka objektivnih kliničkih i dijagnostičkih kriterija otežano. Cilj terapije navedenog sindroma je trojak: snižavanje tjelesne temperature, nadoknada izgubljene tekućine i elektrolita te obnova cirkulirajućeg volumena krvi. Prognoza u slučaju blagog sindroma iscrpljenosti je dobra, dok je kod težih slučajeva zbog mogućih komplikacija pa čak i smrti životinje upitna. Sindrom iscrpljenosti konja moguće je prevenirati odabirom pasmine konja koja je pogodna za veću tjelesnu aktivnost, održavanje zdravlja konja redovitim veterinarskim pregledima, umjereno pojačavanje intenziteta treninga te izbjegavanje napornih kondicijskih treninga kroz više uzastopnih dana. Od izrazite je važnosti procjena zdravstvenog stanja konja od strane jahača tijekom cijelog natjecanja.