Retained Placentas In
Written by Dr. Frederick
Agricultural Extension Service, University of Tennessee
When a foal is born without
complications, the horse breeder relaxes. But, there's an additional event
to be concerned about - passing of the placenta. Don't relax too soon.
Expulsion of the placenta marks the end of the
third, and final stage of labor. Myometrial contractions begin at the tip
of the mare's uterine horn, expelling the placental membranes. Actually,
the allantoic surface is on the outside of the expelled placenta. While
this is occurring, mares may show signs of mild colic, being uneasy,
pawing, lying down and rolling.
The placenta is usually passed within 30 minutes
to three hours after birth. If not passed within three hours, it is
considered a retained placenta, and requires veterinary attention. All or
part of the placenta (allantochorion) may be retained, which occurs in
about 11 percent of foaling mares.
Older mares (15 years old and older) retain
placentas more frequently than younger mares. Retained placentas are more
likely to occur after dystocias, prolonged gestations and cesareans.
A retained placenta can result in metritis,
laminitis (founder), septicemia or even death of the mare. Once a mare
retains a placenta, she is likely to do it again. Poor body condition or
poor environment may increase the incidence of retained placentas. Mares
that retain a placenta usually do not have the normal "colicy"
signs associated with the passing of the placenta.
A placenta protruding from the mare's vulva and
touching her hocks should be looped through itself and tied with binder
twine. This keeps the mare from stepping on it, causing it to tear,
leaving a pierce in her uterus, and keeps her from kicking it in fright,
injuring her foal, Even a small portion of the placenta remaining in the
mare is a serious threat. one may not know that this condition exists
unless the placenta is carefully examined.
When a mare expels the placenta, place it in a
garbage bag and put it in a refrigerator or cool place for your
veterinarian to examine. it is important that there is only one opening in
the placenta, the one through which the foal came. A second opening
indicates that a piece of the placenta may still be in the mare.
Never remove a placenta manually, which can cause
permanent damage to the endometrium. Oxytocin is apparently the most
beneficial treatment. Antibiotics should be given to mares with dystocias,
retained placentas for more than 12 hours, a history of post-foaling
laminitis, fever, or a stinking discharge.
Since mares with a history of retaining placentas
are likely to do it again, treated them with oxytocin immediately after
birth. Wait about 25 days before breeding mares which have had retained
Your veterinarian can also determine if the
placenta is healthy. An unhealthy or diseased placenta can indicate a
potential problem with a new born foal.
In Mares" Glossary
Placenta: A membranous
vascular organ that develops in female mammals during pregnancy,
lining the uterine wall and partially enveloping the fetus, to which
it is attached by the umbilical cord. Following birth, the placenta
Allantoic: A membranous sac that develops from the posterior
part of the alimentary canal in the embryos of mammals, birds, and
reptiles. It is important in the formation of the umbilical cord and
placenta in mammals. Also called allantoid.
Dystocias: ill, hard delivery
Metritis: inflammation of the lining of
Laminitis: Inflammation of the sensitive laminae of the hoof,
especially in horses. Also called founder.
Endometrium: The glandular mucous membrane that lines the
Oxytocin: A short polypeptide hormone released from the
posterior lobe of the pituitary gland, that stimulates the
contraction of smooth muscle of the uterus during labor and
facilitates ejection of milk from the breast during nursing.