Page 474 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.1 The female reproductive tr act 449

VetBooks.ir 2.57 Prognosis
Undiagnosed fetal mummification may result in the
loss of a breeding season, but there are no long-term
effects on the breeding potential of the mare pro-
vided no infection is involved.

EARLY EMBRYONIC DEATH

Definition/overview
Early embryonic death (EED) is defined as death of
the embryo occurring before 40 days of pregnancy
and it can result from many factors. Figures for the
level of early embryonic loss are affected by the tim-
Fig. 2.57 Twin abortion in the last trimester of ing of the pregnancy diagnosis. The highest losses
pregnancy showing clear disparity in fetal size. The occur prior to the routine first pregnancy diagno-
smaller fetus had already died in utero and undergone sis at 14–15 days, with progressively less over time.
early mummification. Many causes have been proposed.
Aetiology/pathophysiology
a normal foaling. Prolonged pregnancy can occur Genetic factors include: embryonic, chromosomal and
beyond the expected term. In some cases the mum- developmental defects; inbreeding; ageing of sperm
mified fetus is trapped in the uterus or cervix after or oocyte at conception; individual mare or stal-
parturition and the mare starts to cycle normally. lion genetic makeup or defects. Management effects
If the fetus undergoes intrauterine maceration, a include: stresses such as hyperthermia, travel and
brown discharge may be seen at the vulva. There are water deprivation; poor nutrition prior to conception
rarely any systemic signs. and in early pregnancy; concurrent systemic illness
or severe or prolonged colic; toxicosis, including drug
Differential diagnosis therapy in early pregnancy. Individual mare factors
Other causes of spontaneous abortion. include: age of the mare (with older mares often hav-
ing over double the rate of loss, mainly due to subfer-
Diagnosis tility); breeding at first post-partum oestrus (foal heat).
Diagnosis is based on clinical signs. Rectal palpa- Uterine abnormalities can lead to a hostile
tion reveals the uterus contracted around a dry, con- environment for the embryo (e.g. delayed uterine
torted fetus with no surrounding fluids. Transrectal involution; endometritis and retained intrauterine
or transabdominal ultrasonography reveals a highly fluid; chronic endometrial disease such as atrophy,
echogenic contracted fetal mass in the uterus. fibrosis and endometrial cysts).
Endocrine causes such as inadequate endogenous
Management prostaglandin production by the CL to maintain
In the late-term mare, delivery can be induced fol- pregnancy have been suggested, but are often dif-
lowing prostaglandin treatment and cervical dila- ficult to prove.
tion, often manually. The uterus should be flushed Other causes include oviduct obstruction, twin-
with sterile saline to aid lubrication of the delivery ning and abnormalities of the embryo location.
and repeated, possibly post delivery, in order to
remove debris and contamination from the uterus. Clinical presentation
If infection is suspected in the case of maceration, Mares return to oestrus following a positive preg-
antibiotics should be given depending on culture and nancy diagnosis either ultrasonographically (14–25
sensitivity results. Caesarean section may very rarely days) or by manual rectal palpation (21–40 days).
be required to remove a large mummified fetus. Variable other signs occur relating to the cause.