Evidence Of Stillbirth Resulting From Fetal Hypoxia During Parturition In The South China Tiger

The South China tiger (Panthera tigris amoyensis) is a tiger subspecies that was native in southern China, and has been classified as critically endangered by IUCN since 1996 as it is possibly extinct in the wild, making it the most threatened tiger subspecies. Captive population in China is suffering from sever inbreeding depression demonstrated as high rate of stillbirth. Previous studies demonstrated that all stillborn fetuses developed fully and normally, the process of pregnancy and parturition were all normal, and the death of fetus occurred during or just prior to parturition. We hypothesized that the stillbirth might be resulted from placental abruption during parturition which led to the break off of oxygen supply, fetal hypoxia and death. In order to prove this hypothesis we use HE stainning to do the quantitative analysis of lung structure of Southern China tiger stillbirths by measuring and comparing the Lm values between the case and control groups, and the stillbirths of Amur tiger and the infant Southern China tigers which died 5 hours after birth were treated as the control group. In order to identify the occurrence of hypoxia or death that resulted from the scant supply of nutriment during the perinatal stage or delivery, we quantitatively analyzed the lung structure of stillbirths of the Southern China tiger. To further infer the main cause of death, we also analyzed the cause and mechanism of the asphyxia. The Lm value among different groups was significantly different with the P value less than 0.05. The largest Lm value was found in the infant male Southern China tigers, and then the stillbirth of female Southern China tiger, the stillbirth of Amur tiger has the smallest Lm value. We also found amniotic fluid components in the alveolar space of the stillbirth of female Southern China tiger. We conclude that the stillbirth of Southern China tiger experienced hypoxia during the perinatal stage or delivery. We infer that placental abruption may occure during delivery, this will result from the hypoxia and futher kill the fetus in the antenatal stage.