Influence of transrectal and transabdominal ultrasound examination on salivary XXXX , heart rate, and heart rate variability in mares.

@entity1641 @entity701 @entity2339
UNASSIGNED: Pregnancy diagnostics in @entity1641 reproduction are routinely performed using transrectal ultrasonography, although it is also possible to visualize the fetus by transabdominal ultrasound examinations from the 90th day of gestation onward. We hypothesized that ultrasound examinations may stress the mare and that the gestational stage status and lactation may influence the mare's stress reaction. To investigate the stress reaction, 25 thoroughbred mares of different age, pregnancy and lactational status underwent a transrectal examination. In pregnant mares, an additional transabdominal examination was performed. Salivary @entity701 concentration, mean heart rate, and heart rate variability of mares were assessed to evaluate the reactions of @entity2339 and of the autonomic nervous system. Significant differences were observed between lactating and nonlactating mares; with a lower responsiveness to stress in lactating mares. The transrectal ultrasound examination in nonlactating mares induced a significant increase in salivary @entity701 (P  <  0.05), and in the heart rate variability parameter, ratio of low to high frequencies (P  <  0.05). This reflects an activation of the @entity2339 and a shift to more sympathetic dominance. In contrast, a transabdominally performed pregnancy check did not induce an activation of the @entity2339 over basal level but increased the mean heart rate and low to high frequency ratio. The results of this study indicate that checks of advanced pregnancies can be easily performed by transabdominal ultrasonography. With regard to animal welfare, this technique should be preferred during midgestation in nonlactating mares.
