The echotexture and morphometric assessment of the uterus and ovarian structures coinciding with hormonal parameters during early gestation of Arabian mares

Abstract

Arabian horses are characterized by distinctive features, such as beauty, athletic performance, and heat tolerance, which are supported by functional and structural genes. Hormonal profiling and ultrasonography (US) are considered non-invasive tools for routine pregnancy diagnosis and evaluation. Therefore, this study aimed to evaluate the uterine and ovarian structures' haemodynamic, echotexture, and morphometric characteristics in relation to the hormonal profile during early pregnancy in Arabian mares. Therefore, 12 Arabian mares with a mean age of 7.6 years were subjected to natural breeding by three fertile Arabian stallions every other day throughout estrus till ovulation was detected by ultrasound (US). After embryonic vesicles were detected on Day (D) 14, blood samples and US examinations were then performed on days 35, 45, and 60 of the pregnancy. A larger (P < 0.05) dominant follicle (˃30 mm) was observed at D 35 with a lower (P < 0.05) uterine echotexture. Whereas the primary and accessory corpora lutea (CLs) size, count, and echotexture showed no significant difference. Conversely, the largest CLs colored areas (mm²) were observed on D 45. Nitric oxide (NO), total antioxidant capacity (TAC), and hormonal values showed no significant differences. In conclusion, these findings suggest that these values are consistent with the normal physiological state of early pregnancy and may serve as a reference range providing a baseline for future research and clinical assessments in this breed. Moreover, the observed larger primary CL colored area on D 45 supports the hypothesis of its resurgence, which reflects the second luteal response to pregnancy in equines.