Evaluating Placentas Can Pinpoint Potential Problems

Although common knowledge among veterinarians, few horse owners know that the condition of a mare's placenta following birth is a useful barometer for gauging the health of a newborn foal. If the placenta appears abnormal, the foal could be at risk for infection that could lead to death. However, if the attending veterinarian recognizes abnormalities in the expelled placenta, he or she might be able to prevent complications the foal could encounter.

Michelle M. LeBlanc, DVM, and her colleagues at the College of Veterinary Medicine, University of Florida, Gainesville, for several years have been observing and researching the link between a mare's placental health and the health of her foal. LeBlanc believes the placenta "is a mirror of the environment" in which the foal lived during gestation. Any abnormalities in the uterine environment during pregnancy might trigger abnormalities in the foal.

"It is very important to examine and evaluate the placenta following birth," said LeBlanc, an equine reproduction specialist. "If the fetus does not receive the proper nutrition, the foal may be smaller, weaker, and more susceptible to infection."

Since it is almost impossible for the average horse owner to determine uterine detachment during gestation, careful inspection of the placenta following birth is important.

LeBlanc recommends spreading the placenta out to see first that it has all been expelled. If the mare retains any portion of the placenta, she might contract an infection, possibly develop laminitis, and she could die within five days of foaling.

Next, LeBlanc recommends the placenta be turned inside out so that it is examined as it was attached normally inside the mare--blue membrane inside, wet, red velvety membrane outside.

"What is normally seen at birth is the inside of the placenta, or the side that lies next to the foal," LeBlanc said. "After foaling, when the placenta begins to detach from the uterus, it turns inside out. You want to examine the outside of the placenta, which lies next to the lining of the uterus. That's where most abnormalities are found."

The placenta should look almost like the color of red velvet. Any discoloration, visible discharge, or attachments that are abnormally short are potential signs of pending complications for the foal. Even if the placenta appears normal to the horse owner, LeBlanc recommends having a veterinarian examine the placenta, mare, and foal. The veterinarian will probably monitor the foal's progress, check its immunoglobulin (IgG) level, and perform a complete blood count (CBC). If the foal appears weak, or its IgG level or CBC are suspect, then it might be necessary to treat the foal with antibiotics or give it supplemental colostrum. (See article on failure of passive transfer on page 37.)

LeBlanc inspects the placenta of all mares she assists with foaling. A sample of all abnormal placentas are examined microscopically to determine what might have triggered the placental abnormalities in the first place; i.e., placental infection, abnormal attachments, or vascular compromise.

While it is important to inspect the placenta following birth, LeBlanc said prenatal care is very important for maintaining placental health. If LeBlanc suspects a mare has placental abnormalities before the mare foals, she will ultrasonically examine the placenta. LeBlanc looks for placental abnormalities such as thickened areas or areas that are not attached to the uterus. Abnormalities could lead to uterine separation or detachment.

Symptoms that might suggest a mare is harboring placental abnormalities would be a vaginal discharge, premature dripping of milk, or a medical crisis such as colic.

"If we find any separation or thickening, we consider the mare to have a high-risk pregnancy," LeBlanc said. "If she is high risk, we either bring her to the vet school, where we can keep her under 24-hour watch, or we leave her at the farm, monitor her closely, and treat her with antibiotics and progesterone."

LeBlanc added that proper environmental management of a mare's surroundings is also a factor in maintaining placental health. Rather than treat a mare with antibiotics for infection, LeBlanc prefers preventing infections. Mares housed in poorly ventilated barns, dirty stalls or paddocks, or subjected to over-crowding or improper nutrition are much more susceptible to stress and infections.

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Aleta Walther

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