Zenyatta's pregnancy was announced via her diary on her Zenyatta blog. Ascertained in foal through a transrectal uterine ultrasound, the fifteen day check-up showed a strong embryo. With her last reported date of cover (mating) as February 23, 2010, she can be expected to foal on or around February 1, 2012.
The next ultrasound, in a week or so, will reveal the fetal heart beat. This ultrasound check up is also used to rule out a twin pregnancy. Subsequent check ups at around 30 , 45 and 60 days after mating ensure that the pregnancy is on track. If Team Zenyatta is curious about the gender of the foal, between 55 and 70 days a veterinary practitioner can make a fairly reliable determination.
By 90 days, the fetus drops out of range of the ultrasound and manual rectal palpation is used to monitor the foal. In cases where there may be concerns about the viability of the fetus or the quality of its life supporting placenta, a transabdominal ultrasound from outside of the mare's abdomen can be performed.
Looking ahead, there is the hope that champion parents will produce extraordinarily talented. offspring. While this has occurred, often high performing mares have been unable to produce at their own level.
It was often thought that the non-producing great mare "left the best part of herself on the track." Perhaps. Until a few years ago, it is likely that those mares were assisted by performance enhancing steroids. Zenyatta's phenom career record of 20-19-1-0 was achieved clean, with no steroids. Therefore, I believe her demonstrated, inherent ability has a better chance of passing to her youngsters. Time will tell.