Placentitis in Donkeys

Placentitis is inflammation of the placenta, the tissue that connects a pregnant jenny to her developing foal. In equids, this problem is most often linked to infection, especially bacteria that move upward through the reproductive tract, though fungal infection and less common focal placental infections can also occur. Because the placenta delivers oxygen and nutrients to the fetus, inflammation can lead to abortion, premature delivery, stillbirth, or a weak newborn.

There is far less donkey-specific research than horse research, so your vet will often adapt evidence from mares while accounting for donkey pregnancy differences. That is reasonable in practice, but it also means careful monitoring matters. Donkey gestation is often around 12 months, and normal pregnancies can vary, so changes in udder development, discharge, or fetal well-being should never be brushed off in a late-pregnant jenny.

Some cases are dramatic, with obvious discharge and rapid decline. Others are quiet at first. A jenny may seem only mildly uncomfortable, start making milk too early, or have subtle ultrasound changes before more serious problems appear. Early veterinary attention gives the best chance to support the pregnancy and prepare for a premature or compromised foal if needed.

Most placentitis cases in equids are thought to be ascending infections, meaning bacteria travel upward through the vulva, vagina, and cervix to the placenta. Organisms reported in mares include Streptococcus zooepidemicus, E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Rhodococcus equi, and Actinobacillus equuli. Fungal placentitis can happen too, though it is less common.

Risk factors often involve anything that makes it easier for contamination to reach the reproductive tract or makes the jenny less able to resist infection. Examples include poor perineal conformation, pneumovagina, previous reproductive tract disease, cervical problems, poor breeding hygiene, and untreated genital infection before breeding. In horses, focal forms such as nocardioform placentitis are also recognized, and these may be harder to detect early because discharge can be absent.

In many donkeys, the exact trigger is never proven during pregnancy. That is why your vet may discuss both likely causes and practical next steps rather than promising a single answer. If pregnancy loss occurs, submitting the fetus and placenta to a diagnostic laboratory can be one of the most useful ways to identify the cause and guide future breeding decisions.

Diagnosis starts with urgency and pattern recognition. Your vet will review the breeding date, expected foaling window, recent udder changes, discharge, appetite, temperature, and any signs of discomfort. A reproductive exam may include careful external evaluation, speculum exam when appropriate, and ultrasound. In equine practice, ultrasound is central because it can assess placental thickness, fluid character, fetal heart rate, fetal activity, and overall fetal viability.

For ascending placentitis in mares, transrectal ultrasound is commonly used to measure the combined thickness of the uterus and placenta near the cervical star. Increased thickness, separation, or abnormal fluid raises concern. In later pregnancy, transabdominal ultrasound may also help assess the fetus and placenta. Because normal reference values are much better established in horses than donkeys, your vet may rely on serial exams in the same jenny rather than one number alone.

Additional tests can include bloodwork, culture or cytology of discharge when safe and practical, and hormone testing in selected cases. If abortion or premature delivery occurs, the placenta and fetus should be submitted fresh or chilled, not frozen, for pathology and culture. That step often gives the clearest diagnosis and can help protect future pregnancies on the farm.

Not every case can be prevented, but risk can often be lowered. Good breeding hygiene matters. That includes using clean breeding practices, identifying and treating reproductive tract disease before breeding, and asking your vet to evaluate jennies with poor vulvar conformation, suspected pneumovagina, or a history of infertility or pregnancy loss. In horses, correcting air aspiration problems with procedures such as a Caslick can reduce ascending contamination risk in selected animals, and your vet can advise whether a similar approach is appropriate for a donkey.

During pregnancy, keep the jenny in good body condition, reduce unnecessary stress, and monitor for discharge, udder development, and changes in behavior. High-risk pregnancies may benefit from scheduled ultrasound checks in late gestation, especially if there is a prior history of placentitis, abortion, or reproductive tract disease. Because donkey gestation can be variable, it helps to track breeding dates carefully and discuss what is normal for that individual jenny rather than relying only on a calendar.

If a pregnancy is lost, prevention for the next breeding season starts with diagnostics. A full exam of the placenta and fetus can reveal infection, inflammation pattern, or another cause of loss. That information can shape future breeding management, monitoring plans, and any pre-breeding treatment your vet recommends.