Fédération Equestre Internationale (FEI) has described equine endurance racing as the second largest discipline in the world, above which is only show jumping. The Žemaitukai is an ancient indigenous Lithuanian horse breed known since the 6th or 7th century. The Arabian horse breed is one of the oldest human-developed horse breeds in the world. Compared with other race horse breeds, the muscle tissue of Arabian horses is characterized by significant differences in structure—a predominance of oxidative fiber type I is observed in Arabians, making them the prevailing breed in endurance racing. The Arabian horses are recognized as the leading breed in endurance competitions. Speed, pace, and total time in the race strategy have been extensively studied in human sports, and in contrast, this strategy appears to have been virtually ignored in equestrian sport, despite the potential for contributing to performance optimization. In relation to speed and total time in the race, there are limited data on postrace physical, biochemical, and blood gas parameters of endurance horses. Thus, this study was carried out to investigate the effects of speed on the blood parameters of the Arabian and Žemaitukai horses during an endurance race. Blood samples were taken before and immediately after the exercise. Biochemical and blood gas indicators were analyzed. The study showed significant increases in mean blood gasometrical indicators, such as partial carbon dioxide pressure (8.09–15.18%, p < 0.001); base excess in the extracellular fluid (14.01%, p < 0.001 in the Arabian horses and 172.01% in the Žemaitukai breed, p = 0.006); decreases of the blood electrolyte ionized calcium (4.38–8.72%, p < 0.001) and the hematocrit and hemoglobin values (20.05–20.12%, p < 0.001 in the Arabian horses and 6.22–6.23% in the Žemaitukai breed, p = 0.003–0.004); and decreases in the base excess in the blood values (29.24–39.38%, p < 0.001) and lactate (13.45–31.97%, p < 0.001) in the blood of both breeds in the post-competition horses. Significant increases after competition were determined for the values of creatinine (21.34–30.82%, p = 0.001–0.004), total bilirubin (50.84–56.24%, PH < 0.001), and albumin (2.63–4.48%, p = 0.048–0.001) for both breeds. For the faster Arabian horse breed, recovering after racing took half the time that the local Žemaitukai breed did.

Ovarian tumors in mares are uncommon in comparison to other neoplasms and are classified into three categories: gonadal stromal tumors, coelomic epithelium surface tumors, and germinal cell tumors. Some ovarian neoplasms histologically show a mixture of multiple cell types in the same tumor, such as fibrothecoma; therefore, the differentiation between fibroma and thecoma is often difficult. According to the World Health Organization, fibrothecomas are classified as sex-cord stromal tumors (pure stromal tumors). Neoplasms such as fibrothecoma present with limited morphological, clinical, ultrasonographic, and endocrine profile characteristics. To diagnose this type of tumor, a broad clinical examination is needed, but histopathology remains the most accurate. Herein, we report a case of incidentally found ovarian fibrothecoma during a diagnostic laparotomy in a 6-year-old Dutch Warmblood (KWPN) mare who presented to the clinic with colic symptoms. After a unilateral ovariectomy, the altered right ovary was diagnosed as fibrothecoma based on histopathological features.

Ovarian tumors in mares are not common in comparison to other neoplasms and are divided into three categories: gonadal stromal tumors, coelomic epithelium surface tumors, and germinative cell tumors [12]. Some ovarian neo-plasms histologically show a mixture of multiple cell types in the same tumor, such as fibrothecoma, therefore the dif-ferentiation between fibroma and thecoma is often difficult [1]. According to World Health Organization, fibrothecoma is classified as sex cords stromal tumor (pure stromal tumor) [13]. Neoplasms, such as fibrothecoma have a very scarce morphology, clinical signs, ultrasonographic view and endocrine profile. To diagnose this type of tumor, a broad clini-cal examination is needed, but histopathology remains the most accurate. Herein, we report a case of incidentally found ovarian fibrothecoma during diagnostic laparotomy in 6-year-old KWPN mare which was presented to the clinic with colic symptoms. After unilateral ovariectomy, the altered right ovary, based on histopathological features was diag-nosed as fibrothecoma.