A single mummified fetus was removed from the uterus of a 23-year-old
mare that had been bred approximately 30 months previously. The mare h
ad received supplemental progestin therapy for approximately 150 days
after ovulation. This case represents the longest recorded occurrence
of fetal mummification in the mare. Progestin administration may have
contributed to the initial retention of the fetus in the uterus.