A normal placenta should be complete and have two very different looking sides, the pregnant horn (in which the fetus resided, and the non-pregnant horn, a smaller and more shriveled horn).

Unless you have the opportunity to see many mares foal, and have looked at many placentas, trying to distinguish between a normal and abnormal placenta may be impossible for you, and should best be left to your vet.

That said, there are some basic things that you can look for: The side in contact with the foal should appear pale, pink and clean. The side that was in contact with the uterus should be velvety red. You may see spots of brown discoloration and liquifying of that red surface, which is normal decomposition of the surface that happens rapidly, especially during warm weather.

The placenta should be complete, meaning that there should be tips to both horns. (See the related media image.) Often, the mare or foal step on the shed placenta and it may be damaged.

If if even a small piece of placenta is retained inside the mare, this can cause a life-threatening infection that must be addressed quickly.

If you have any question about the appearance of your mare's placenta after foaling you should immediately contact your vet.