The Puerperium - Horse Anatomy

The puerperium is short, with rapid involution and good conception rates at the first postpartum oestrus.

Involution

Lochial discharge is slight in most mares and usually ceases 24-48 hours after foaling. Uterine horns shrink rapidly, reaching pre-gravid size by day 32 postpartum. The cervix remains slightly dilated until after the first oestrus. Involution delayed by retained foetal membranes, as in other species.

Restoration of the Endometrium

The endometrium is capable of sustaining a pregnancy (fully restored) by 13-25 days postpartum. Small amounts of villous debris attached to maternal crypts are removed by autolysis. Maternal cryps disappear due to:

• Lysis
• Shrinkage of endometrial epithelial cells
• Condensation of contents of epithelial cells
• Collapse of the crypt lumen

Return to Ovarian Cyclicity

This is rapid in the mare. Foal heat occurs 5-12 days postpartum. Follicular activity after day 2 postpartum.

Bacterial Elimination

Bacterial contamination of the uterus from the environment is frequent. Organisms are usually eliminated during foal heat or disappear at second postpartum oestrus.