University of wisconsin-madison

Signs of Parturition - Mammary Gland

Adominal distention becomes very apparent during the last 2 weeks of gestation. However the degree of distention is less in the first pregnancy and more in subsequent ones.

As parturition approaches the mammary gland will begin to enlarge. This may occur as much as 2 - 3 weeks before parturition. As parturition gets closer, the enlargement will increase and the teats will begin to fill with milk. Proteins present in the pre-milk secretion increase near the time of parturition and the pre-milk begins to leak out of the teats. The coagulation of the proteins as this secretion dries forms a wax-like secretion. The wax is not seen in all mares but is generally present 24 - 72 hours before parturition. In some mares the wax may be seen 10 or more days before parturition and may come and go. It is important to remember that a mare may foal without the formation of wax. If you observe rapidly dripping white secretions, that may or may not be forming wax, this indicates oxytocin release and the mare is in the early stages of labor.

If the pre-milk secretions are collected, there will be a change in milk color from clear or amber to chalky white. This change usually occurs during the last 48 hours before parturition. It is also possible to allow the pre-milk to dry between your fingers and the tackiness increases as parturition approaches.

This image shows the typical swelling of the mammary gland prior to parturition, swelling of the teats and the secretion of the wax.
Here the swelling of the mammary glands and teats are visible. This mare had no wax secretion prior to foaling.
A very early sign that the mammary gland is filling is the white dots that are present in this image around the teat. This is a pre-milk secretion that appears on the surface of the teat.
This is a image of waxing that occurred within 3 hours of foaling in this mare and is much different that the first image shown above.
A pre-milk secretion collected on the day before foaling. Note that the color is chalky-white.

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