Comparison of two ultrasonic methods for multiple pregnancy diagnosis in sheep and indicators of multiple pregnant ewes in the blood

Abstract

Single and multiple pregnancies in sheep were diagnosed to compare the accuracy at day 80–95 of gestation by an ultrasonic Doppler method (Doppler) and a real-time linear ultrasound scanning method (Scanning). In order to investigate indicator(s) of multiple pregnant ewes, plasma total protein, total cholesterol, glucose and progesterone were measured in 37 pregnant and 26 non-pregnant ewes. For predicting single or multiple (⩾ 2 fetuses) pregnancy, the Doppler method resulted in a higher rate of accuracy in both single (82.6%) and multiple (92.9%) diagnoses than those by the Scanning method (68.2% and 66.7%, respectively). However, there were no significant differences between the accuracy of the methods, and between single and multiple diagnoses. Plasma total protein and total cholesterol concentrations did not significantly differ between non-pregnant and pregnant ewes, and between single- and multiple-pregnant ewes. Plasma glucose concentrations in pregnant ewes were significantly lower than in non-pregnant ewes (2.3 ± 0.05 vs 2.6 ± 0.07 mmol/1; P<0.01). Also, glucose concentrations were significantly lower in multiple-pregnant ewes compared with single-pregnant ewes (2.2 ± 0.08 vs 2.4 ± 0.07 mmol/1; P<0.01). On the contrary, plasma progesterone concentrations in pregnant ewes were significantly higher than in non-pregnant ewes (4.9 ± 0.38 vs 1.7 ± 0.22 ng/ml; P<0.01). Concentrations of plasma progesterone in multiple pregnant ewes were significantly higher than in single-pregnant ewes (5.8 ± 0.53 vs. 4.2 ± 0.49; P<0.05). There was a high correlation coefficient ( r=0.783) between concentrations of plasma glucose and progesterone in pregnant ewes bearing triplets, but this relationship was non-significant. The only inverse relationship was found in non-pregnant ewes. The present study indicates that the Doppler method may be useful for multiple pregnancy diagnosis at day 80–95 of gestation, and that both plasma glucose and progesterone concentrations are indicators of pregnant ewes bearing multiple fetuses.