Unusual phenomena during pregnancy in the cat and cow

Unusual situations were observed during examination of pregnant uteri from a cat and a cow. The feline specimen revealed three corpora lutea at the surface of each ovary with three fetuses developing normally in the left and two in the right uterine horn. The right horn had been ruptured between two of the locular enlargements but the damage was sealed by the omentum. Three conceptuses were present in the cow's uterus. Two of these embryos, each with its individual allantois, were developing within a single chorion within one uterine horn. The adjacent tips of these allantoic vesicles were entangled into a complex knot which could provide opportunity for vascular anastomosis.