Friesian mares have a higher incidence than normal for retaining the fetal membranes (placenta) after foaling. One study that observed the foaling out of 495 Friesian mares concluded the occurrence of retained placenta was as high as 54% in Friesian horses compared to a rate of 10% or less in other breeds. Normally, mares pass the placenta without assistance within three hours of foaling. The time allotted for safe passage of the placenta (3 hours or less) is due to the fact the placenta begins to break down and become necrotic almost immediately after it is separated from the uterus and blood flow to the placenta has stopped. At this point, the placenta can be considered a decaying piece of tissue, and if it is left in the uterus for several hours, a serious and life-threatening infection can easily follow. Bacteria and infection can enter the bloodstream via the uterus, and sepsis can occur, setting off a chain reaction in the body and causing laminitis and subsequent founder. Thus, a retained placenta is nothing to take lightly, and if it remains more than three hours after the mare foals, it should be treated as a medical emergency.
What causes a retained placenta? Two issues can contribute to a retained placenta. The most common issue occurs when the mare’s uterus does not contract enough, and the heavy placenta cannot be expelled. Alternatively, the mare’s uterus may contract too much, and the Velcro-like microvilli that help the placenta connect to the uterine wall are forcefully pressed against the wall during exceptionally strong contractions, which then cause the placenta to become reattached to the uterine wall. The most common treatment for a retained placenta is to administer a dose of Oxytocin to induce uterine contractions. Oxytocin promotes uterine contractions and facilitates the release of microvilli that hold the placenta in place. This method of treatment will often address a retained placenta that is the result of a lack of strong contractions. If Oxytocin is not successful, other common treatments include administering a large volume uterine lavage or a method called the “Burn’s Technique”. With the Burns Technique, a veterinarian infuses the inside of the placenta with fluid via a nasogastric tube while holding the placenta closed at its opening with his/her hand. When fluid is infused into the placenta, it expands, causing a natural oxytocin release and abdominal contractions, which facilitate the placenta’s release and passage.
A more recently developed method called the “Dutch Technique”, developed by Dutch Veterinarian Mark Meijer, involves infusing water directly into the umbilical cord vessels. Dr. Meijer has treated more than 150 mares with this method and collected extensive documentation, achieving a 92% success rate of expelling the placenta. This creative method causes the placenta’s vascular system, including the microvilli, to expand and stretch, allowing the placenta to release from the uterus. To accomplish the Dutch Technique, a stallion catheter (or tube with a similar diameter) is attached to a garden hose fitting with a stoppage lever. An incision is then made into one of the umbilical vessels, and the stallion catheter is threaded into the umbilical vessel as far as possible. The hose stoppage lever is turned to the “on” position, and the umbilical vessel is slowly infused with water under low pressure while the veterinarian holds the vessel closed and prohibits water from leaking. At the same time of infusion, gentle traction is placed on the placenta. Infusion of the placenta takes approximately 5 minutes or until water begins to reflux from the umbilical vessel. The placenta separates from the uterus and is slowly expelled from the uterus.
It is important to note both the Burns Technique and the Dutch Technique are most effective when the placenta has not been retained for an excessively long period of time (8-12 hours or less), and both methods require that the placenta is still intact and has not begun to severely decompose and break down. As with any foaling, the placenta should be examined carefully once removed to ensure that pieces were not retained. It is usually prudent to treat mares that have retained the placenta for more than 12 hours with antibiotic and anti-inflammatory medication and to initiate laminitis prevention methods such as ice boots.
The overall prognosis for mares with a retained placenta who are treated early is generally very good, with most mares regaining their reproductive health by their 30-day heat cycle. Cases with more serious complications have a guarded prognosis, especially when laminitis or founder have developed.
Video of “Dutch Technique” courtesy of Animal Reproduction Systems (ARS).
Video of the “Burn’s Technique” courtesy of Foundation Equine Clinic. https://www.facebook.com/watch/?v=2543393072572485
Animal Reproduction Systems (ARS) Retained Placenta Kit, designed for administration of the “Dutch Technique”. https://www.arsequine.com/retained-placenta-kit
References:
Retained Placenta in Friesian Mares: Incidence, and Potential Risk Factors with Special Emphasis on Gestational Length. M Sevinga 1 , H W Barkema, H Stryhn, J W Hesselink. 2004.
Managing Retained Managing Retained Fetal Membranes in Mares. April 3 rd , 2018. A. King. The Horse.
Afterbirth Quickly Expelled With ‘Garden Hose Method’. March 20 th , 2019. The Phryso
