"I think one of the most common postpartum complications that is sometimes overlooked and that can have severe consequences
is retained placenta," Wolfsdorf explains. Retained placenta — still attached to the endometrium after three hours — is the
most common postpartum complication (see Photo 5). The nonpregnant horn is more commonly retained than the edematous pregnant
horn. It has an incidence of up to 10 percent. According to Wolfsdorf, "higher incidence has been reported in draft mares,
mares of increased age and cases of prolonged gestation, hydrops, abortion, stillbirth, twinning, dystocia, placentitis and
Photo 5: This photo depicts a retained placenta. The placenta is tied in a knot hanging from the vulva to apply tension through
gravity on the endometrial attachment.
Retained placenta may not be obvious, such as when the whole placenta is retained and hanging from the vulvar lips. "Occasionally,
just the tip of a nonpregnant horn may be retained, and if you don't examine the placenta routinely and completely, you can
easily miss a piece of placenta," Wolfsdorf says. "If you miss a piece of placenta, then you set yourself up for metritis,
endotoxemia, septicemia and laminitis. Eventually, the mare may end up with serious complications. Make sure you examine each
placenta completely. Turn it inside out so that the velvety or chorionic surface can be viewed since this is the surface against
the endometrium and is most likely to show pathology. In addition, you will be able to identify the tips of both horns by
the avillus portion where the oviductal papillae resides."
"With a normal mare that has retained her placenta, I will start uterine lavage as soon as I examine the mare," says Sheerin.
"If a majority of the placenta is retained intact, we perform the Burns technique, in which the placenta is filled with fluids
and the fluids are held in the placenta for a period of time. We then remove that fluid and treat the mare with a small dose
of oxytocin. Most mares will pass their placenta after this treatment. These mares are also given systemic antibiotics and
For mares that have had a uterine artery bleed as well as retained placenta, the procedure is somewhat different. "I will
wait probably 24 hours before I start to do anything with the mare, and then the things I do, I do in slow increments," says
Sheerin. "I will examine her and perhaps do a little bit of gentle manipulation to allow the placenta to be passed." If the
mare stops pushing and enough of the placenta is sitting in the uterus, there's not enough gravity to pull it out. If you
can exteriorize a portion of it, then gravity will kick in and slowly break down the attachment, and the mare will pass it.
But don't start just tugging on it; gentle traction will suffice.
"If I do lavage on these mares, which I generally start within 24 to 48 hours after foaling, I use small volumes of fluid
so I'm not distending the uterus too much," says Sheerin. "A liter or two, flushing it in and out, is adequate. I may do that
many times to try to dilute out any potential bacteria, so we avoid dealing with septicemia or endotoxemia as well."
Obviously life-threatening, most cases of periparturient hemorrhage occur in older, multiparous mares. But, recently, it is
increasingly seen in primiparous mares of almost any age, 5 to 24. "Hemorrhage may occur from the middle uterine, external
iliac, utero-ovarian or vaginal/vestibule-vaginal arteries in late pregnancy and after parturition, and it accounts for 40
percent of periparturient deaths in mares," states Wolfsdorf.
You can see different levels of hemorrhage in these mares. A mare may hemorrhage prior to foaling and exhibit mild, colic
signs, or you may find the mare dead. More commonly, a mare hemorrhages after foaling, which may occur from a couple of hours
to a couple of days postpartum. "The majority of mares hemorrhage postfoaling or within 24 hours of foaling," says Sheerin.
"But we've had mares that hemorrhage prefoaling as well as mares that hemorrhage as far as a week out from foaling."
Three different types of hemorrhage can occur, according to Wolfsdorf. First, mares can rupture a uterine artery and bleed
into their broad ligament. This type is usually self-limiting, contained within the ligament by hematoma formation. Affected
mares may be mildly to moderately painful and will usually show signs of colic and discomfort and eventually develop mild
signs of shock.
A second, more severe and more life-threatening type occurs when the hemorrhage leaks out of the broad ligament intra-abdominally,
and the mares go into full-blown shock.
The third type involves intrauterine hemorrhage in which there may be an artery or a blood vessel within the uterus that leaks
or is torn during parturition, and the mares bleed into their uterus. "That is usually a more subtle scenario in which you
may just find blood coming out of the mare's vulva when she walks or lies down since the uterus gets full," says Wolfsdorf.
"When she moves around, there may be a trickle of blood or clots that come out of her uterus."
Veterinarians have a variety of options to treat these mares. "In my experience, it is important to keep mares quiet in a
dark stall and keep them sedated, if needed, as well as comfortable with anti-inflammatory agents such as banamine," says
Sheerin. "Once we determine that a mare is indeed bleeding, we'll use naloxone, which is an opiate antagonist useful for treating
shock, and sedation. We may start the mare on fluids and use aminocaproic acid, which is used in people with hyperfibrinolysis-induced
hemorrhage, plus or minus corticosteroids as well as additional fluids. Using fluids obviously is controversial, in that are
you going to possibly increase the blood pressure too much by increasing the volume or replacing the volume. Nobody has come
up with an answer because it is something that is hard to do any sort of controlled study on, so the evidence is only anecdotal.
Thus, the decision is made on a case-by-case basis."
Sending these mares to a referral clinic may add additional stress, increasing blood pressure and possibly causing the broad
ligament to rupture. "If there is a complete rent in the broad ligament because of the bleed, and the mare is bleeding profusely
into its abdomen, then there is nothing you can do to save it," Sheerin says.