I do not need to tell everyone that late gestational abortion in mares can be so very upsetting. After all the effort, time, and resources that is spent on establishing pregnancy, it is really awful to lose one. Although nature sometimes terminates a pregnancy for unknown reasons, mares and their unborn foals can become subject to diseases like any other horse. Placentitis is the number one cause of infectious abortion in mares.
The placenta is the fetal organ which interacts with the mare's uterus for the delivery of nutrients and removal of wastes. Placentitis is inflammation of the placenta, which is most commonly caused by bacterial infection. There are three forms of placentitis: Ascending, Hematogenous, and Nocardioform. Briefly, Ascending comes from the vagina and cervix. Hematogenous is from the blood and Nocardioform is a very specific type caused by a single microorganism. This cause is almost only diagnosed in Kentucky. Advances in diagnostics have enabled veterinarians to detect the Ascending form of placentitis via ultrasound examination. Measurements are taken of the thickness of the uterus and placenta and these values let us know if problems are occurring. Treatments are aimed at antibiotics, anti-inflammatories, and hormonal supplementation. Early treatment has been shown to lengthen gestation and have a more favorable outcome to the foals than untreated mares.
I strongly recommend to my clients and all horse owners to have their mares examined as part of a pre-natal health program. If anyone has any questions about this disease, please feel free to contact me.
Take care all and think healthy foals.
Justin T. Hayna, DVM, Dipl. ACT
