A rare and unusual case of advanced complete molar pregnancy in an Arabian mare: first report.

Molar pregnancy is a rare condition in women, referring to the development of fetal membranes with or without an embryo. A 22-year-old mare referred to the veterinary faculty clinic due to the delayed parturition. In the ultrasound examination, the uterine membranes were seen suspended in fluids without any trace of the fetal organs. The mare underwent caesarean section, a mixture of brown fluid with fragments of fetal membranes was removed, but no fetus or any remnants of the fetus were found in the uterus. In the histopathological examinations, the fetal membranes showed severe degenerative changes. Also, the thickness of the endometrium had lost its normal structure and the layers of stratum spongiosum and stratum compactum could not be separated. The contents of the uterus were evacuated as much as possible and the mare regained her full health after the surgery. This is the first case of continued pregnancy without an embryo in a horse, which can be an unusual type of molar pregnancy.