Complications in the postpartum (‘post foaling’) period can occur following dystocia (‘a difficult birth’) or following a relatively normal delivery. Although these complications are uncommon, when they do occur they can be potentially life threatening or detrimental to a mare’s fertility. Early diagnosis and prompt intervention gives the best opportunity for survival.

A large proportion of complications that can occur in the postpartum period have the initial clinical sign of abdominal pain or colic. This abdominal pain may be due to disorders affecting primarily the gastrointestinal or the reproductive tracts. Other important clinical parameters useful in the diagnosis and differentiation of postpartum problems are heart rate, respiratory rate, rectal body temperature and mucous membrane colour.

Large colon torsion is the most common cause of colic requiring surgical treatment and mares are at greatest risk of developing this condition in the first 100 days’ post foaling. Clinical findings most often include acute, violent abdominal pain with progressive abdominal distension, although this condition can be associated with more mild-moderate abdominal discomfort. Following torsion of the colon the blood supply to the gastrointestinal tract becomes compromised, leading quickly to clinical signs of systemic inflammation (‘shock’). These signs include a significant increase in heart rate, respiratory rate and deterioration in mucous membrane colour (dark pink, purple). Gastric reflux can also occur in a third of cases. A definitive diagnosis of a large colon torsion is achieved via exploratory laparotomy (colic surgery); although palpation per rectum of a distended gas filled large colon and thickening/oedema of the large colon wall on abdominal ultrasound are findings highly suggestive of this condition. The survival rate in cases of large colon torsion is increased by early surgical intervention and aggressive intensive veterinary and nursing care. Post-operative management of these mares includes intravenous fluid therapy, anti-inflammatory agents, medications to bond circulating toxins, gastro-protectants and foot cryotherapy (to aid in the prevention of laminitis). These mares are at risk of secondary complications including repeat torsion, chronic colic, secondary infections and laminitis.

Uterine tears can occur following normal and complicated deliveries. These mares typically show mild-moderate signs of abdominal pain, and are dull, appetent and have a fever. A full thickness tear in the uterine wall results in contamination of the abdomen with foetal fluid and causes septic peritonitis. An increase in free peritoneal fluid is often evident on abdominal ultrasound and an abdominocentesis (or belly tap) will confirm the peritoneal fluid is septic. If a large defect is present herniation of abdominal contents may also occur. Exploratory laparotomy is recommended in the majority of these cases. This allows the uterine tear to be identified and closed, whilst large volume lavage of the abdomen to dilute contamination can also be performed. These mares also require intensive post-operative veterinary and nursing care incorporating intravenous fluid therapy, broad spectrum anti-microbials, anti-inflammatory agents, medications to bind circulating toxins, gastro-protectants, oxytocin and foot cryotherapy. An indwelling abdominal drain is often placed so the abdomen can be lavaged daily. The prognosis for these mares depends on the duration of illness, degree of abdominal contamination and the degree of secondary compromise to the gastrointestinal tract. These mares are at risk of secondary complications including adhesion formation, chronic colic and laminitis.

Rupture of uterine arteries is a serious, extremely painful and potentially rapidly-fatal post foaling complication. Multiparous mares (mares who have had a number of foals) and older mares are at increased risk of middle uterine artery rupture. This is considered to be associated with an age related deterioration in the integrity of arterial walls. Rupture of the uterine arteries can result in haemorrhage into the ligaments that support the uterus (broad ligament) or haemorrhage into the abdomen of the mare. Haemorrhage into the broad ligament causes severe pain, anxiety, sweating, an increased heart rate and pale mucous membranes. Swelling at the vulva and perineum may also be evident. Haemorrhage into the abdominal cavity causes abdominal discomfort followed closely by signs of shock. If the haemorrhage is severe death will result quickly. Luckily, not all cases of intra-abdominal haemorrhage are fatal. A haematoma can often be palpated during rectal examination, confirming haemorrhage into the broad ligament, whilst a characteristic 'swirling’ pattern of blood on abdominal ultrasound can be useful in confirming the presence of an intra-abdominal bleed. Obtaining blood on abdominocentesis (belly tap) is also confirmatory for intra-abdominal haemorrhage. These mares are most commonly treated with intravenous fluid therapy, whole blood transfusions, broad spectrum anti-microbials, anti-inflammatory agents, medications to promote clot formation, gastro-protectants and analgesia (pain relief). Keeping affected mares as calm as possible is also important to try to avoid further bleeding. The prognosis for these mares depends on the severity of the haemorrhage that has occurred and the ability of clot formation to occur.

The post foaling mare normally passes her foetal membranes within three hours of foaling, although this can be delayed for up to 8-12 hours without signs of illness. Retained foetal membranes more commonly occurs in mares following abortion, dystocia and caesarean section. The cause of the condition is unknown, however may involve disturbances to normal pre-partum endocrine events or myometrial (uterine muscle) contractility. The retained placenta may be visual at the vulva, although in some cases only a portion of the placenta (‘tag’) remains attached. Most commonly the non-gravid (non-pregnant) uterine horn of the placenta is retained. The longer the time frame the mare’s placenta is retained the greater the risk of potential complications occurring, including metritis (infection of the uterus), systemic inflammation and laminitis. These complications can be avoided by prompt treatment and removal of the membranes. Treatment combinations of oxytocin, uterine lavage and gentle traction/manual manipulation often results in release of the membranes. If the membranes remain adhered beyond 8-12 hours, then systemic broad spectrum anti-microbials and non-steroidal anti-inflammatory drug treatment should also be utilised.

If you have any questions or concerns regarding your mare or foal during the breeding season, please contact the Scone Equine Hospital’s Clovelly Intensive Care Unit (02) 6545 1433.

Dr Lucy Cudmore

BVSc (Hons) MVSc MANZCVS DipECEIM

Specialist in Equine Medicine

Scone Equine Hospital, Clovelly Intensive Care Unit

Scone, NSW, Australia