Retention of tubal eggs in mares

Genital tracts from 227 mares slaughtered in various reproductive states were investigated to study egg retention in the oviducts. Eggs were found in 88-2% of 212 non-pregnant mares; the number/mare ranged from 0 to 21, and averaged 4-34. Retained eggs were twice as common in heavy as in light breeds and were found more frequently in early than in late pregnancy. Eggs were not found in the oviducts of two anovulatory post-partum mares. A few globular masses, probably consisting of desquamated tubal mucosa, were frequently lodged in the distal region of the ampulla and appeared, to some extent to cause the retention of more eggs.