Abstract

Dexamethasone is a potent synthetic glucocorticoid use in veterinary and human medicine. However, it causes intra uterine growth restriction (IUGR) and decreases birth weights in some animal species and humans, although each species respond differently. This study investigated the effects of dexamethasone on placental weights and some foetal parameters in Yankasa sheep and Sahel goats with known average gestational length of 148.35 ± 1.50 days and 148.33 ± 1.58 days respectively. Ten adult Sahel goats comprising 8 does and 2 bucks and 10 Yankasa Sheep comprising of 8 ewes and 2 rams were used for this study. Pregnancies were achieved by natural mating after synchronization. Repeated dexamethasone injections were intramuscularly given at 0.25mg/kg body weight on days 1, 3 and 5 during first trimester and days 51, 53 and 55 during second trimester.  Foetuses were harvested at day 78 of gestation all through Caesarean section.  Foetal weights, crown-rump lengths (CRL), height at withers, heart girth, abdominal circumference, weights of adrenal glands and placental weight were evaluated. Specimens from placentas and adrenal glands were collected for histological analysis. Results showed that the mean placental weights, placental efficiency and foetal body weights were significantly (P<0.05) decreased in dexamethasone treated sheep and goats compared to controls. There was no significant change in foetal adrenal glands and linear body measurements between dexamethasone treatment and control groups in both species except crown-rump lengths (CRL)which was significantly (P<0.05) reduced in Sheep foetuses. It was concluded that dexamethasone caused significant decrease in placental weights and placenta efficiency and hence placental- maternal- foetal transport of nutrient materials in both species and also caused decrease in foetal crown-rump-lengths in sheep but not in goats. This suggests that dexamethasone has some teratogenic effects and that Sheep are more susceptible to dexamethasone treatment compared to goats.

Keywords: Dexamethasone, Foetuses, Placenta, Pregnancies, Sahel goats, Yankasa sheep