Postpartum Problems in Mares
A post-foaling injury or infection can be life-threatening or career-ending for a mare.
Photo: Anne M. Eberhardt/The Horse
I remember 1973 as a bad year. We had three mares foaling, and two had problems. The first mare wasn't producing much milk and also had severe uterine cramps after foaling. We administered pain-relieving drugs and monitored her to make sure she didn't crash down on her new foal. Eventually the crisis passed.
The second mare was not so lucky; her foal presented backward. (During a normal birth a foal faces the back of the mare, with head down and legs stretched out and straight like a diver, but this was not so in our mare's case.) Our veterinarian extracted the foal--dead by then--and discovered the mare had a tear in her uterus; she was later euthanized.
According to Ryan Coy, DVM, of Royal Vista Southwest, an embryo transfer and mare management center in Purcell, Okla., things can go wrong a couple of times during foaling: during parturition (the act of giving birth), especially if there's a dystocia (difficult birth), and immediately after.
The first thing owners should do after a mare foals is ensure she is bright and alert. "Most mares want to eat something and have a drink of water," says Jerry Black, DVM, director of undergraduate programs in equine sciences at Colorado State University. "We like to have a small amount of hay available to help us know if the mare is normal post-foaling. If she's not interested in food, this could be an early sign there's something wrong."
Black says he also makes sure the mare is producing enough milk. "The baby needs a full complement of antibodies from (the mare's) colostrum within the first four to six hours," he says. "Foals that are continuously trying to nurse or bumping the udder are not getting enough, and you need to call your veterinarian. The only sure way to make sure the foal has adequate passive transfer (of these antibodies from the mare) is to run an IgG test on the foal's serum. This should be done between eight and 16 hours after the foal is born."
Even if everything seems normal, have your veterinarian perform a post-foaling exam to assess the foal and examine the mare.
Owners should check and save/refrigerate the placenta (the organized tissue in the uterus that joins the fetus to the mother) for the veterinarian to examine, says Ahmed Tibary, DVM, PhD, Dipl. ACT, professor of theriogenology in Washington State University's, department of veterinary clinical sciences. "Just assuming it is complete and throwing it away is not a good idea, because the placenta is where a lot of answers can be found."
The mare should pass the placenta within 30 minutes to three hours after she foals. A retained placenta is the most common post-foaling problem in mares of any age as well as one of the most serious because it can lead to complications such as toxemia (blood poisoning caused by bacterial toxins) or laminitis (an inflammation of the laminae--interlocking leaflike tissues that attach the horse's hoof to the coffin bone within it).
It's important to address a retained placenta quickly. "If it's retained more than six hours, management of the case must be much more intensive than when it is still fresh," says Tibary, noting that cases involving field foaling can be particularly problematic to approach because you might not know exactly when the mare foaled. "If the placenta is retained, we don't know whether it's been two hours or three hours."A common cause of retained placenta is the premature pulling apart of the placenta from amniotic membranes that encase the foal. Coy explains, "Sometimes the amnion is torn away from the placenta when a nervous or inexperienced mare inadvertently steps on the amnion, or when we're assisting delivery (during dystocias)."
Tibary says that a treatment plan should be devised after examination of the mare to determine why the placenta was retained. "Some breeds are predisposed to placental retention," he explains. "These include draft horses and Miniature Horses. In these breeds part of the problem may be hypocalcemia (shortage of calcium). Without treating this situation, you are not addressing the real problem."
A treatment plan includes uterine lavage with large volumes of fluids, oxytocin (to increase uterine contractions and aid with the uterine emptying as well as expulsion of the retained placenta), anti-inflammatories, antibiotics, and anti-endotoxic drugs. The intensity of the treatment will vary with each particular case.
Retaining a small piece of placenta "can cause a problem just as severe as if the whole placenta was retained," says Tibary. "It's easy to see the problem when the placenta is hanging there, but more difficult to make that judgment when it has already been passed--particularly if foaling was unobserved out in the field and the placenta is missing or has been torn apart."
"Placental tags still attached inside the uterus ... can be life-threatening," says Coy. This is because the uterine bacteria overgrows, and then the bacterial toxins (as in endotoxemia cases) or bacteria itself (as in sepsis) can gain access to the mare's bloodstream and cause a severe systemic disease or laminitic event.
Coy says it's important to note that if the placenta is abnormal, the mare should not be bred back on foal heat (the first heat period after parturition). Her uterus should be given time to heal and provide a healthy environment for the embryo.
Occasionally the birth canal is bruised or lacerated if the foal's hooves scrape or perforate the vaginal wall. This injury is most common in first-time foalings, but it also occurs in some mares experiencing dystocias or giving birth to large foals.
"These injuries can be complicated by infection or aggravated by severe inflammation," says Tibary. "Simple vaginal bruising may be painful enough to prevent the mare from urinating or defecating."
Because of the proximity of the rectum to the vagina, the mare might experience great discomfort when passing feces and subsequently develop a gastrointestinal impaction, which could be worse than the vaginal injury itself. An owner might prevent an impaction by providing laxative feeds such as bran mash so bowel movements will be softer and the mare can pass them more readily and with less pain.
Rectal-vaginal tearing (whereby the foal's foot or nose breaks through the top of the vagina and into the rectum during parturition) is another common injury. A vaginal or vulva tear or a rectal-vaginal tear will be immediately noticeable after parturition (as a discernable laceration or, with a rectal-vaginal tear, when feces exit from the rectum directly into the vagina and are expelled from the vulva), but repair should wait until after the inflammation and swelling subside.
"Surgical repair of a rectal-vaginal tear is usually performed after a healthy bed of granulation tissue is established over the wounds," says Coy. Therefore, unlike with a retained placenta, mares that sustain these injuries can be bred back via artificial insemination or live cover after the perineal area is thoroughly cleaned. After the mare is in foal, surgical repair can then be performed. The mare's cervix (oval-shaped mass whose opening connects the uterus with the vagina) provides an adequate barrier to uterine contamination from feces during early gestation.
According to Coy, these types of tears are rarely life-threatening, but should be repaired to preserve a mare's fertility.
While vaginal and vulvar tears can be resolved uneventfully, cervical injuries can be much more detrimental to a mare's breeding career. Cervical lacerations occur most often due to severe dystocia and extreme efforts by veterinarians or managers to reposition and extract the foal.
Coy notes that cervical lacerations are not readily apparent until uterine involution (when the uterus contracts to nonpregnancy size after parturition) is almost complete. Veterinarians generally diagnose these injuries when the mare is not in heat and the cervix is closed, or they become evident when breeding the mare at her 30-day heat. "Major cervical lacerations require surgical repair, but the outcome is often less than optimum," he says, adding that these lacerations can inhibit a mare's fertility and her potential to carry a pregnancy.
Many mares--particularly during first foalings--experience mild to moderate uterine cramps due to continued uterine contractions following foaling. They might also lie down to expel the placenta. According to Black, these signs aren't cause for concern. "Cramping is usually transient and normal, but you need to watch the mare," he says. "If pain continues or she becomes violent, this may be an indication of a serious condition."
Therefore, some mares (particularly maiden mares) require a dose of a mild analgesic after foaling. You should also monitor the mare to ensure she doesn't injure the foal if she rolls.
"Discomfort from uterine contractions can usually be managed with a single dose of veterinary-prescribed sedation and medication such as Banamine (flunixin meglumine)," says Coy. "If the mare doesn't respond and within 30 minutes is still showing pain or becoming uncomfortable again, call your veterinarian. There may be more going on than uterine contractions. She may have a ruptured uterine artery (see the "hemorrhage" section) or trauma to the large colon."
The mare's colon might become trapped and suffer contusion or bruising during foaling, or it might be pinched between the foal and pelvic canal. "If it is seriously damaged there will be necrosis (tissue death) and compromising of the gut wall integrity," says Coy. "Pathogenic microorganisms then cross that barrier--from the gut into the abdomen--and the mare will develop peritonitis (inflammation of the lining of the abdomen). In these cases she will be dull and show colic, but these signs are usually not evident right away."
Coy says the mare's prognosis depends on peritonitis severity and gut wall integrity. Sometimes a veterinarian can manage a contusion of the colon successfully if he or she initiates appropriate treatment early. "Often the mare won't show distinctive clinical signs, making early diagnosis and treatment difficult," says Coy.
"If there's complete rupture of the cecum or right ventral colon, ingesta (ingested feed) spills into the abdomen," he continues. "The mare develops severe peritonitis, endotoxemia, and sepsis rapidly. These mares you probably won't be able to save unless you know there's a problem and can perform abdominal surgery and lavage immediately. In most cases, by the time the mare shows signs of acute peritonitis and sepsis, vascular collapse (shock) and death will follow within hours. It's too late for effective life-saving measures."
There are several other reasons for colic after foaling. "Many mares become mildly dehydrated. They may not want to pass manure because of abdominal pain--especially if it's their first foaling--and they may become impacted (see vaginal injury section)," says Black. For the first few days after foaling, mares also are prone to displacement colic. There might be displacement of the colon if it shifts into the suddenly empty space after the foal is born and the uterus is involuting.
Sometimes during a dystocia--and most commonly with older mares--one of the foal's feet (or nose) might scrape or tear the uterine wall itself. Clinical signs of a tear (also called a uterine rupture) can include extreme depression, lack of appetite, illness, and possible colic. A mare with a uterine tear usually can be saved if she receives immediate veterinary treatment to repair the tear. However, if the tear is too large or the cervix is involved, her prognosis as a broodmare is guarded to poor.
Less Common Problems
Uterine Hemorrhage One of the most critical emergencies for a mare after foaling is bleeding from the uterine blood vessels (arteries), or a hemorrhage, which occurs most commonly in older mares. "This may (last) hours or a few days, depending on extent of hemorrhage," says Tibary.
The most catastrophic hemorrhage occurs when a uterine artery (which supplies the uterus) ruptures and the mare bleeds uncontrollably into the abdomen.
Coy explains, "This condition becomes painful, as there's distension of the broad ligament (the structure that helps suspend the uterus in the abdominal cavity), and colic symptoms may be an early indication of a potentially life-threatening problem."
If a uterine artery ruptures and bleeds directly into the abdomen or nonconfined space, you generally cannot get the mare to a medical facility quickly enough for life-saving efforts. "But if you catch the mares that are acting painful early on, you can decrease their activity and keep them calm (and possibly minimize damage)," explains Coy. "Your veterinarian may administer a drug like aminocaproic acid to maintain the blood clot integrity."
Bladder Prolapse Occasionally the bladder is pushed out (protrudes) from the vulva during or immediately after foaling. "In mares, bladder prolapse is relatively common after severe dystocia, because the urethral opening in the mare is so large," says Tibary. This emergency situation requires immediate veterinary examination.
Uterine Prolapse Prolapsed uterus in mares is rare but, similar to a bladder prolapse, obvious when it happens because abnormal tissue protrudes from the vulva. Prolapse occurs most often immediately after birth, but it also can occur up to three or four days later. This situation also requires immediate veterinary attention.
Immediate treatment is critical to your mare's prognosis if she experiences any postpartum problems. Discuss potential issues and develop a plan of action with your veterinarian before foaling--have him or her examine the mare and the placenta post-foaling. If you plan to breed your mare back on foal heat, first have your veterinarian conduct a pre-breeding exam to ensure her uterus is healed and healthy to carry another foal.
About the Author
Heather Smith Thomas ranches with her husband near Salmon, Idaho, raising cattle and a few horses. She has a B.A. in English and history from University of Puget Sound (1966). She has raised and trained horses for 50 years, and has been writing freelance articles and books nearly that long, publishing 20 books and more than 9,000 articles for horse and livestock publications. Some of her books include Understanding Equine Hoof Care, The Horse Conformation Handbook, Care and Management of Horses, Storey's Guide to Raising Horses and Storey's Guide to Training Horses. Besides having her own blog, www.heathersmiththomas.blogspot.com, she writes a biweekly blog at http://insidestorey.blogspot.com that comes out on Tuesdays.
POLL: University Equine Hospitals