Diagnosis of Pregnancy in Pigs by Real Time Ultrasonic B-mode Scan

Abstract

Ultrasonic tomography was carried out for pregnancy diagnosis of sows or gilts with a portable real time ultrasonic B-mode scanner. The probe of the scanner was placed in contact with the abdomen of an unrestrained standing sow. Many gestational sacs (GS) in the uterus appeared on the ultrasonograms during a period of 18-21 days after coitus. Pregnancy was diagnosed by the presence of GS, fetal or embryonic echo. A clear diagnosis of whether they were pregnant or not could be made for almost all pigs tested from 22 days after coitus, and the accuracy rate for pregnancy diagnosis was 100%. Mean diameter of GS increased rapidly (about 6mm/day) until 25 days after coitus (y=6.97x-128.02, r=0.89). GS were mostly circle or oval at their first appearance, and then they changed to various forms. Various sizes of GS were observed in the same animal. Feeble embryonic echo came to be confirmed about 25 days after coitus, and the exsistence of many large GS made the diagnosis easy. In the pigs after mid pregnancy, the body and head of the fetus could be distinguished. Since fetal heart movements could also be observed, recognition of fetal death was possible. The fetuses were distributed irregularly in the uterus in various directions. No abnormalities in litter size and gestation period were observed in the pigs examined. These results indicate that the real time ultrasonic B-mode scan is extremly effective for early pregnancy diagnosis in swine in the field.