The objectives of this study were to investigate incidence of embryonic deaths and some efficient factors causing embryonic and fetal losses and to demostrate applicability of ultrasonography in detecting embryonic deaths in purebred Arabian mares.

Fifty nine pregnant Arabian mares aging between 4 and 27 years old were used as material. The pregnancy was detected 16 days after mating. Ultrasonographic examination was performed 20, 40, and 60 days after mating in order to determine incidence of embryonic death. The total incidence of embryonic death was 16.9%. The highest incidence of embryonic death was detected between 20^th and 40^th days. With regard to age, embryonic death was found 3.8%, 12.5% and 41.1% in mares aged 4 to 9, 10 to 16 and, >16 years, respectively. Embryonic deaths were higher (P<0.05) in mares, >16 years oldcompared to 4 to 9 years old. Furthermore, embryonic deaths were 21.7% from March 1 to May 15, 13.8% from May 15 to end of July and there was no significant difference among these periods. According to their reproductive status, embryo loss rates were found as 7.1%, 23.5%, and 9% in foal heat, cyclic heat, and maiden mares, respectively and in any case, the data obtained in all groups were not statistically different. Embryonic death rate was 37.5% in mares with previous infertility problem.

As a result, ultrasonography is a reliable and easily performed method in detecting embryonic death of mares. Periodical examinations are necessary for determining approximate foaling rate in embryonic stage. Furthermore, it was concluded that factors such as age, season or reproductive status might be effective as alone or combined for occurance of embryonic death. Further studies investigating other factors are, therefore, necessary for a better understanding of embryonic and fetal losses.