Page 497 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

472 CHAPTER 2

VetBooks.ir should be examined once they have been passed by 2.78
laying them out in an ‘F’ shape to check that they are
intact, identify any tears or shortening of the horns
that would suggest some membrane is retained, and
check that there are no abnormalities that may affect
the neonate.

Management
The approach to retained fetal membranes varies
considerably depending on the duration of mem-
brane retention and the presence/absence of metritis
with septicaemia. If the retained fetal membranes
are trailing down the hindlimbs of the mare, and
especially below the level of the hocks, they should
be tied up to a level with the hocks so that they do Fig. 2.78 A retained placenta being gently retrieved
not interfere with the limbs. The tying of an addi- from the uterus after treatment with oxytocin.
tional weight to the retained fetal membranes is not
recommended as it may predispose to uterine pro-
lapse or tearing of the membranes, but it is used by may be accompanied by mild discomfort during
some clinicians. the process.
Accelerating the release of the fetal membranes Manual removal of the placenta is generally
is best achieved in the first 6–8 hours post partum not advised as it leads to uterine haemorrhage,
by the use of oxytocin administered intravenously increased damage and fibrosis of the endometrium
(10 IU for a 500 kg horse) or slowly (over 15 min- and increased uptake of endotoxins and bacteria.
utes) in intravenous fluids (50 IU in 500 ml saline, Aggressive removal can predispose to uterine horn-
may be repeated after 2 hours), or intramuscular tip invagination and prolapse and/or small parts of
injections (10–20 IU) repeated every 15–60 min- the placenta remaining in the uterus. Some clini-
utes. In the latter part of the post-partum period, cians feel that gentle traction and twisting of the
doses of oxytocin may need to be increased slightly placenta is helpful during uterine lavage in order to
to achieve uterine contraction. If oxytocin therapy encourage separation.
alone is unsuccessful, manual removal can be per- Prevention of secondary complications and their
formed where the allantochorion is twisted on itself aggressive treatment are important and should be
to encourage detachment from the endometrium. initiated if the membranes are retained beyond
Alternatively, the allantochorion can be distended 8 hours (3–4 hours in draught, heavy breeds).
via a sterile stomach tube with 10–12 litres of warm Broad-spectrum antibiotics are indicated unless
saline/water +/− mild antiseptic solutions (<0.5% specific culture and sensitivity results are available.
povidone–iodine) and maintained for up to 30 min- Anaerobic organisms can be involved and are often
utes to stretch the uterus (possibly releasing endoge- treated with metronidazole or penicillin. NSAIDs,
nous oxytocin), detach the microvilli of the placenta especially flunixin meglumine, are particularly
and encourage passage (Fig. 2.78). useful for their antiendotoxic effects. If the mare
Recently, an infusion of water into the allan- becomes endotoxic, intravenous fluids are essential
tochorionic blood vessel has been shown to be to maintain the cardiovascular system and major
effective in removing retained fetal membranes. organ function. It is important to check electrolyte
The umbilical blood vessels are catheterised using levels and supplement if necessary. Tetanus prophy-
a foal stomach tube and a constant rate of water laxis should be checked and boosted if required.
infused (stomach pump or from a tap). The pla- The feet of the mare should be supported by placing
centa is usually passed within 5–10 minutes and them on sand, peat or a small shavings deep bed, or