Determining Fetal Age
While it is possible to estimate fetal age from distinquishing features during rectal palpation, it is more accurate to determine it using ultrasoundography.
| Determining early fetal age can be done by comparing the diameter of the vesicle to the graph. Ultrasoundography is used to determine the diameter of the embryonic vesicle. |  |
It is very difficult to determie the fetal age of fetuses older than 50 days since the final size of the foal may be very different depending on genetics. Determining fetal age later than 100 days can be done by ultrasoundography and measuring fetal eye size as shown in the graph below. (McKinnon, AO and EL Squires, 1986. Proc. 4th Ann. Short Course Equine Ultrasound, Colorado Stae University, Fort Collins, CO pp 11-35)
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