Macroscopic evaluation of the placenta of the alpaca (Vicugna pacos)

Macroscopic evaluation of the placenta is an essential post-partum examination in the alpaca and can be of special interest in case of abortion, premature birth or stillbirth. Since there are not many reference values regarding macroscopic properties of normal alpaca placentas, a small descriptive study was conducted. Only placentae from normally foaling alpaca mares, giving birth to healthy crias, after a full-term and uneventful gestation (±350 days; range 335-360 days) were taken into account (N = 11). Crias weighed (±SD) 7.7 ± 2.25 kg (range 5.5-10 kg), while the mean weight of the full-term placentas was 0.8 ± 0.19 kg, that is 10% of the bodyweight of the crias. The weight of the allantoamnion and chorion was 0.2 ± 0.07 kg and 0.5 ± 0.13 kg, respectively. The umbilical cord length was 8.8 ± 2.84 cm, and the length of the pregnant and non-pregnant uterine horns was 69.4 ± 12.77 cm and 54.5 ± 6.81 cm, respectively. The length of the corpus was 14.6 ± 4.68 cm, and the distance from the umbilicus to the corpus was 18.5 ± 6.13 cm. The tissue volume of the allantoamnion was 0.14 ± 0.079 L, and the chorionic volume was 0.37 ± 0.078 L. The surface area of the allantoamnion and the chorion was 87.6 ± 15.56 dm² and 72.3 ± 9.28 dm² , respectively. All placentas had small calcifications either around the umbilical cord alone or around the umbilicus and blood vessels of the pregnant uterine horn. These measurements could be used to macroscopically evaluate alpaca placentas, although more research is needed to extend our knowledge of macroscopic evaluation of normal and abnormal placentas.