Horse Illustrated Magazine

Q: Can you explain what a red bag delivery is? I have a mare that is due to foal this month, and I’ve been told to watch for this complication.

A: “Red bag delivery” is a layperson’s term for premature separation of the placenta prior to or during a mare’s foaling. Fortunately, it is an infrequent occurrence in healthy foaling mares. However, when it does occur, prompt action is required to prevent a stillborn or weak foal.

The foaling attendant must know that the equine placenta is made up of two major parts: the red bag or chorioallantois, and the white bag or amnion. The red bag attaches to the uterine wall and allows the exchange of nutrients and waste back and forth to the fetus through the umbilical cord. The white bag surrounds the fetus and has many functions, including lubrication and protection. During a normal foaling, the red bag breaks just prior to the foal entering the birth canal. Thus, the first portion of the placenta you see in a normal foaling is the amnion, or white bag, followed promptly by the fetus it contains.

In a normal delivery, the red bag is generally passed by the mare within three hours after foaling. When the red bag appears before the white bag, it means that a portion of the placenta has detached from the uterine wall prematurely, reducing or eliminating the exchange of nutrients to the fetus still inside the mare. In this situation, the red bag appears as a red “velvety” bag hanging from the vulva. When the foaling attendant confirms the presence of the red bag instead of the white bag, he/she should carefully open this bag with surgical scissors—inside will be the white bag enclosing the fetus. Check for two legs and the nose; tear open the white bag and deliver the fetus promptly as it may be short on oxygen due to the early placental separation. The foal should be watched carefully for signs of hypoxia (oxygen deprivation) or infection.

Why do red bag deliveries occur? The normal chorioallantois is relatively thin and breaks easily during birthing. However some placentas are thickened from infection or inflammation, a condition called “placentitis,” and can result in red bag deliveries. Exposure of late pregnant mares to fescue grass can also result in a thickened placenta at foaling. High-risk mares that have had abortion, stillborns or weak foals previously can be evaluated by ultrasound in late pregnancy for placentitis or a thickened placenta. Also keep in mind that even a well-handled red bag delivery may result in a compromised foal.

Andy Schmidt, DVM, MS, Diplomat ACT, is based in Oconomowoc, Wis., at the Wisconsin Equine Clinic & Hospital.