Page 464 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.1 The female reproductive tr act 439

VetBooks.ir may achieve adequate concentrations to be effective be used. Clenbuterol, a beta-agonist tocolytic agent
used regularly in human medicine, may not be
against Escherichia coli and Klebsiella spp., it does not
cross the placenta well enough to be effective against
tion in her nutritional intake, a prompt response is
Streptococcus equi. For these reasons the broad- effective in equines. If a pregnant mare has a reduc-
spectrum potentiated sulphonamides are the most necessary as this can lead to premature parturition.
commonly used antibiotics in cases of placentitis. When the ‘high-risk’ mare gives birth she should
A swab of the vulval or cervical discharge should be remain under full veterinary attention together
taken via speculum examination to identify organ- with the foal. In placentitis cases the fetus may or
isms and determine antibiotic sensitivity. There is may not be infected, even if the placenta appears
no evidence that NSAIDs are able to prevent abor- grossly infected.
tion by the inhibition of cyclo-oxygenase-induced An assessment of the likely risk category of the
prostaglandin release, but they may be useful in live foal born from a high-risk pregnancy will greatly
mares suffering from any form of endotoxaemia. improve the survival of that foal. Many such foals
Exogenous progesterone (altrenogest) has been are ‘high risk’, can rapidly deteriorate and require
shown to stop cloprostenol-induced abortion in intensive assessment and treatment (e.g. IgG assay,
experimental models and it has a place in the treat- intravenous plasma, intravenous fluids, antibiotics,
ment of mares with placentitis. A dose higher than supplementary oxygen).
the standard dose (0.088 mg/kg p/o q24 h) should

COMPLICATIONS OF PREGNANCY

UTERINE TORSION Clinical presentation
Most gravid mares with uterine torsion present with
Definition/overview abdominal pain that is mild and intermittent, but it
Uterine torsion is an uncommon condition that may become more severe depending on the degree of
usually occurs in mid to late gestation, but rarely torsion, subsequent tension on the broad ligaments
at parturition. The aetiology is unknown. The and/or pressure on the uterine wall. Secondary GI
condition usually presents as abdominal pain, complications and uterine rupture due to necrosis
often low grade and intermittent, and the diag- will exacerbate the clinical signs and worsen the
nosis is confirmed by rectal palpation. Treatment prognosis. Rarely, torsion at parturition can lead to
using a rolling method under general anaesthe- dystocia. The abdominal pain signs can be misinter-
sia has been suggested, but most cases are treated preted as an impending parturition.
surgically.
Differential diagnosis
Aetiology/pathophysiology Abortion or premature parturition; GI tract colic;
Usually occurs in the last trimester of pregnancy hydrops amnion/allantois; uterine rupture (see
(>7 months), but only occasionally in association p. 466); ventral abdominal wall rupture; prepubic
with parturition. The cause is unknown, but severe tendon rupture; and two other conditions described
trauma, violent rolling (e.g. with a gastrointestinal briefly below:
[GI] tract problem) or fetal righting reflexes may
be involved. The cervix is rarely involved. Older • Fetal hypermotility is the term used for violent
mares are more susceptible. The torsion causes an or excessive foal movements in late pregnancy.
interruption in the uterine blood/lymphatic system, The cause is unknown. If the condition persists,
hypoxaemia of the fetus leading to fetal compromise it is treated with smooth muscle spasmolytics.
and demise, or neonatal conditions such as peripar- • Uterine dorsoretroflexion is when the fetus
tum asphyxia syndrome. impacts in the pelvic canal during the last