NONINVASIVE MONITORING OF FETAL HEART-RATE DURING THE LAST 10 DAYS OFGESTATION IN SOWS

Objective-To develop and evaluate a noninvasive technique for monitori ng and analyzing porcine fetal heart rate (FHR) during late gestation. Animals-8 fetuses of 8 pluriparous sows in late gestation. Procedure- With the sow positioned in lateral recumbency, the most caudal fetus w as identified, using real time ultrasonography, and its heart rate was recorded for 60 minutes by use of Doppler cardiography. The same fetu s was identified and monitored repeatedly during the last 10 days of g estation, excluding the 24 hours before delivery. Visual inspection an d computerized analysis of the recordings were performed. Results-66 o ne-hour recordings were obtained from 8 fetuses, 1 in each of 8 sows. Mean signal loss was 37.5%. Episodes of low FHR and low FHR variation (FHR pattern A) alternated with episodes of high FHR and high FHR vari ation (FHR pattern B). This cyclic alternation between 2 distinct FHR patterns was observed in 46 of 66 (69.7%) recordings, and suggests the presence of different behavioral states in fetal pigs. Basal FHR decr eased toward parturition in 7 fetuses, but increased in 1 fetus with a bdominal ascites. Basal FHR and long-term FHR variation were negativel y correlated (r[S] = -0.73; P < 0.001). Conclusion-Noninvasive monitor ing of FHR is possible and feasible during late gestation in pigs. Thi s method permits longitudinal studies under pathophysiologic condition s and the evaluation of the effects of endogenous and exogenous influe nces on porcine FHR.