Placentitis is an infection of the mare’s placenta, usually occurring within the last 3-4 months of gestation. It can be an extremely devastating condition for the owner both emotionally and economically, as it can be a difficult condition to treat and still may end with a nonviable fetus. The earlier this condition is identified, the better the chance is of treatment working and resulting in a healthy baby.

90% of cases of placentitis result from an ascending infection through the mare’s vagina and migrating through the cervix. This bacterial contamination results in thickened fetal membranes and premature separation of the placenta from the mare’s endometrium. All of this results in decreased oxygen and nutrients to the growing fetus. Also during this process, white blood cells are responding to the infection and producing both pus and pro-inflammatory mediators which may result in abortion of the foal. Common signs of placentitis include premature udder development or lactation and sometimes vulvar discharge. In addition, often the thickened placenta can be seen on ultrasound along with separation of the membranes. Hormonal blood tests can be helpful in cases where it is unclear if placentitis is occurring.

Treatment of placentitis is multifold and includes appropriate antibiotics to treat the infection, along with medications to decrease the inflammatory response. Also, typically these mares are put on Regumate to help block the pro-inflammatory mediators and try to stop uterine contractions from occurring.   Also other drugs may be added to the regimen to help the blood flow to the foal hoping to improve viability.

If a mare delivers a foal prematurely, the fetal membranes need to be examined closely for any signs of thickening or other signs of infection. Also if placentitis is suspected, the veterinarian needs to be involved immediately as even though some of the foals can appear normal at birth, they will often decline rapidly. The sooner treatment can be instituted, the better the chance of a healthy foal.

Also if a mare does have placentitis, after foaling a culture of the uterus should be done and subsequent treatment based on the culture otherwise their ability to get pregnant and maintain a pregnancy may be hampered.

There is one other type of placentitis (not from a bacterial infection) that we see commonly in our area called fescue toxicosis which results from mares eating large amounts of endophyte infested tall fescue. The endophyte in tall fescue produces alkaloids that can affect multiple critical hormones in the mare that have effects throughout the body and can cause a number of issues including a thickened placenta, abortion, retained placenta, prolonged gestation and a lack of milk production by the mare once the foal is born. Prevention is the best treatment, so the recommendation is not to graze broodmares on fescue in the third trimester of their pregnancy. There are oral medications including domperidone that can be helpful in treating the agalactia (not producing milk) part of this form of placentitis, however again often these foals are not as healthy as normal foals due to them not absorbing as much oxygen and nutrients while in utero due to the thickened placenta, plus they are not receiving vital nutrients and antibodies (colostrum) from the mare if she is not producing milk.

If you have any questions about your broodmare’s risk for this condition or see any clinical signs described in this article, please call your veterinarian immediately.

Colic emergencies in late term mares pose an exceptional challenge to veterinarians and owners, as the diagnostic information usually obtained on a rectal examination and abdominal ultrasound are extremely limited due to the large size of the fetus. Furthermore, abdominal surgery carries significant risks to the mare and foal both at the time of surgery and then at foaling. Anesthesia poses risks to both mare and foal, and the foaling puts tremendous stress on the still healing abdominal incision.

These were the concerns present when Kim Schmidt brought her mare,  O’Susannah, into the clinic on March 28 for colic. The 15y old Holsteiner mare was due on April 2 and was already starting to bag up. The mare had been treated at the farm by Keswick Equine Clinic for 36 hours but Susie continued to be persistently painful and had passed no manure. On admission to BREC, we had some concern that the mare had a colon displacement but we could not definitively rule out a simple impaction. After 48 hours of aggressive fluid therapy, there was no improvement and we felt it was time to take a look.  At surgery, a right dorsal displacement was identified. This proved a difficult one to correct due to the large fetus sitting on top of the colon, but ultimately we were successful. The mare did very well under anesthesia and recovered nicely. She was immediately comfortable after the procedure and made steady progress over the next few days. Abdominal ultrasound on April 1 revealed a normal heart rate for the fetus.  Next, it was just a question of getting through delivery.

The colic and surgery seemed to set back the clock on the progress toward foaling. Susie’s bag had disappeared and when she returned to the farm on April 4, foaling did not seem imminent. This was actually a good thing as it bought more time for the healing of her abdominal incision. Soon her udder was enlarging again and our excitement, along with a tinge of anxiety, began to build. At 9 PM on April 12 (almost 2 weeks from the surgery), Susannah was in labor.   Although there were a few complications on delivery, namely mecomium in the amniotic fluid, partial early separation of placenta (red bag delivery), and an enlarged umbilical cord, Kim and her husband were able to assist the mare in a successful delivery and O’Susannah delivered a big vigorous colt and her abdominal incision was unfazed by pressure.

Both mare and foal have continued to do well and we thank Ms. Schmidt for the pictures and for allowing us to tell this story. Over the years we have had a number of colic surgeries on late term mares and, to date, all mares have recovered and had healthy foals.

Kim Schmidt, a Grand Prix Dressage rider, is the breeder, owner, trainer of O”Susannah and lives with her husband on their farm, Grayson Farm, near Scottsville, Va. where she runs a breeding, boarding, training business: https://www.graysonfarm.net

Kim adds:  O’Susannah is a home bred who has had successful careers in Eventing at the 2 star level as well as Jumpers, Fox Hunting and Dressage at the FEI Intermediare 1 level. She has also had three foals. She will return to the Dressage ring with Kim after the weaning of “Dino” registered name: “Don Dinero”. (Translated: “Mr Money”, because it took alot of money to get him here)!

All the best to Kim, Susannah and Dino!