The use of ultrasonography for pregnancy diagnosis in the bitch

Twenty-three Greyhound bitches housed at 3 breeding kennels were examined for pregnancy via transabdominal palpation and ultrasonography. Pregnancy was timed from the calculated day of ovulation (day of ovulation = day when first pup was whelped--63), and from a single breeding date (day 0). Starting on day 10 after ovulation, 9 bitches were monitored every 3 days by ultrasonography only, to determine gestational vesicle sizes during gestation and the time when fetal movements and heartbeats could be first detected. The other 14 bitches were examined by ultrasonography and transabdominal palpation on the same day every week, starting on postovulation day 19, to compare the effectiveness of the 2 methods of pregnancy determination. Parturition was the final determinant of pregnancy status. The earliest correct diagnosis of pregnancy was at 18 days after ovulation, but fetal movements and heartbeat could not be identified until days 28 and 35, respectively. Estimation of fetal numbers by ultrasound or palpation was not reliable when there were more than four in the litter. Pregnancy and nonpregnancy were correctly determined by both methods in an increasingly greater number of bitches as gestation progressed, but ultrasonography was more accurate at all stages; on days 19 to 22, 26 to 30, 34 to 38, and greater than 40 after ovulation, correct diagnoses were made in 33%, 42%, 50%, and 75% of the bitches by palpation and in 42%, 67%, 75%, and 83% of the bitches by ultrasonography. The most common error was failure to detect pregnancy by palpation or ultrasonography in bitches with small litters and tense abdominal muscles.(ABSTRACT TRUNCATED AT 250 WORDS)