The diagnostic method of sheep ultrasound should be selected according to the breeding time and body size of the sheep. Generally, within 50 days after the sheep is bred, the fetus is small and the position of the uterus does not change much. The uterine shape can be observed through the rectum, and it can be determined whether the sheep is pregnant. However, after 50 days of breeding, with the development of the fetus, the shape and position of the uterus have changed greatly. It is difficult to observe the shape of the uterus if it is only located in the rectum, so it is impossible to make a correct judgment. However, if the sheep is large or after a full meal, it is also difficult to observe through the rectum, and it is necessary to combine the abdominal wall diagnosis to make a judgment.

It is most reliable to judge the pregnancy of sheep based on fetal heart beats. Through the sheep sheep ultrasound, the amniotic fluid, cotyledons, fetuses, fetal peristalsis and fetal heart beats in the uterus can be observed. If only watery substances or cotyledons are found in the uterus, it may be uterine hydrops or the fetus has been aborted, and it cannot be regarded as a normal pregnancy. However, as long as the peristaltic fetus and fetal heart beats are observed, it can be determined that the sheep is pregnant. Of course, if there is no obvious change in the observed uterine shape and position, the sheep can be temporarily placed in the non-pregnant flock and a judgment can be made after reexamination.