Ultrasonographic uterine changes and vaginal discharges following intrauterine infusion of liquid paraffin in cows

This study was conducted to examine uterine changes and uterocervical discharges following intrauterine infusion with liquid paraffin (LP) during the luteal phase by ultrasonic and vaginoscopic examinations in cows. Multiparous dairy cows (n=10) were infused with 50 ml physiological saline (PS group; n=5) or liquid paraffin (LP group; n=5) on day 10 or 11 after ovulation (day 0: ovulation). Vaginoscopic, rectal and ultrasonogaphic examinations were carried out at 0.25, 1, 2, 3, 4, 6, 8, 12 and 24 h after the LP and PS infusion and then at daily intervals until subsequent ovulation after the infusions. The mean volumes of recovered discharges from the vagina within 6 h after infusion were significantly greater (P<0.05) in the LP group than in the PS group (33.0 +/- 9.9 vs.14.0 +/- 13.9 ml). Yellowish-white discharge was first observed at 3.2 +/- 0.5 and 3.6 +/- 0.6 h after infusion and lasted for 12.2 +/- 2.9 and 2.1 +/- 1.5 days for the LP and PS groups, respectively, showing a significant difference (P<0.05) in duration. Subsequently, transparent discharge appeared again 2-3 days before the subsequent ovulation after the treatments in both groups and disappeared on the day prior to or the day of ovulation. During the immediate examination after the infusion, the cavity of the uterine horn appeared anechoic and dilated in the images of both groups. The anechoic images changed to echoic images at 2.2 +/- 0.8 and 2.6 +/- 0.9 h after the infusion in the LP and PS groups, respectively, and the echoic images lasted for 12.2 +/- 2.9 and 2.1 +/- 1.5 days in the LP and PS groups, respectively. These results suggest that the appearance and disappearance of intrauterine anechoic and echoic images reflect the appearance and disappearance of the characteristics of the recovered LP/PS-like liquid and yellowish-white and transparent discharges from the vagina.