EQUINE NEWS

DYSTOCIA IN MARES: WHEN EVERY MINUTE COUNTS

Fortunately, in most cases, the mare gives birth to a healthy foal. But in some situations the foal doesn’t arrive as expected or scheduled, resulting in dystocia, or a difficult birth. When that happens, every minute counts if you’re going to save both mare and foal. Anything that interferes with this normal delivery process can result in dystocia. In the mare, causes can include uterine inertia (failure of the uterus to contract correctly, giving the foal inertia to pass through the birth canal), body wall tears, uterine tears, or systemic disease. Problems such as fescue toxicity (from grazing endophyte-infected tall fescue in late gestation) and electrolyte imbalances that alter the uterus’ or placenta’s normal function can put mares at increased risk of dystocia. In addition, if the mare is frightened or stressed, she might position in hypoxia, or herself in a way that prevents the foal from aligning correctly for delivery. Finally, problems can arise if the cervix fails to relax, tissues prolapse, or the foal’s feet get caught at the top of the birth canal. Patricia Sertich, MS, VMD, Dipl. ACT, associate professor-clinician educator at the University of Pennsylvania School Veterinary Medicine’s New Bolton Center, in Kennett Square, says that incorrect fetal posture and positioning is by far the most common cause of dystocia in the horse. Both stress the importance of recognizing another cause of dystocia—a red bag delivery. In a red bag delivery the chorioallantois doesn’t rupture, and the fetus can be expelled encased in all the membranes. When this happens the foal loses its placental blood and oxygen supply and can die. Instead of first seeing the fetus surrounded by a white membrane as it passes through the birth canal, you see a velvety mass at the mare’s vulvar lips. The most serious risk to both mare and foal in the event of a dystocia is death Plain and simple, if the foal doesn’t come out, the mare will die. For the foal, a delay in delivery can result lack of oxygen, that could cause lifelong abnormalities,or it can incur trauma associated with delivery process. Suggest closely observing mares in late gestation. Typical gestation length ranges from 321 to 365 days. Within the month leading up to foaling, mammary development occurs, and the teats fill with milk two days to one week prior to foaling. At this point it’s important to provide round-the-clock observation. You can monitor sodium, potassium, calcium, and pH levels in the mammary secretions, which usually begin 48 hours before parturition (birth). However, mares with abnormal pregnancies that have been dripping milk might not show these changes. Veterinarian perform at least one late gestational transrectal ultrasound and, if possible, a transabdominal scan on the mare around 300 days. This often helps the veterinarian catch abnormal thickening of the placenta, changes in fetal fluids that indicate fetal stress, and, occasionally, fetal abnormalities. This information can help you better prepare for a possible issue. it is vitally important to be prepared, discuss options, and make decisions with your veterinarian so you can implement an emergency plan rapidly. This will increase your chances of ensuring the health and welfare of both mare and foal if a dystocia occurs.