We can accurately diagnose pregnancy using ultrasound at 26 days after breeding.  Ultrasound is probably less traumatic than rectal palpation and the viability of the embryo can be confirmed by the presence of a beating heart.  Other advantages of ultrasound include accurate diagnosis of twins, very accurate fetal aging, and sexing.  The main disadvantage of using ultrasound is that special facilities are required to work quickly and protect the machine.  

Initially look for the presence of uterine fluid, which increases as the pregnancy advances.  The embryo is present around 20 days, and a heart beat is around 21 days.  By day 25, the embryo appears C-shaped.

By day 30, the amnion is visible around the embryo, and the fore and hind limb buds appear.  Distinct limb buds are present at day 35, distinct cranium and umbilical cord by day 40, split hooves by day 45, and ribs by day 53.  Approximate embryonic length sizes at 25, 35, 45, 55, and 60 days of gestation are 5, 15, 30, 45, and 60 mm in length respectively. 

Images of Ultrasounds and more information:




Copyright 1999-2001
New Bolton Center Field Service Department
Students:  Keith Javic - Class of 2003, C. Nikki Conroy - Class of 2003