The use of real-time ultrasound rectally for early pregnancy diagnosis in sheep.

Three groups of ewes (n=64) were tested for pregnancy using a real-time ultrasound system rectally, beginning at Day 25 after breeding. The ewes were examined while standing, using a 5 mH(3) transducer designed for equine rectal use. Each examination required less than one minute and produced no apparent distress. The results of the test compare favorably with other methods of early pregnancy detection with a predictive value of a positive test of 97%, a predictive value of a negative test of 80% and an accuracy of 91%.