abdominal pain whereas, if the vessel bleeds into the abdominal cavity, the initial
signs will be those of acute blood loss such as a rapid weak pulse, rapid shallow
breathing, cold extremities and pale mucus membranes. In the case of a bleed into
the abdominal cavity, the diagnosis is often presumptive since progression may be
too rapid to allow a full work-up. Moreover, the prognosis is grave since even blood
transfusion is generally inadequate to maintain perfusion and oxygenation, while
attempts to identify and ligate the bleeding vessel are unlikely to be successful.
Haemorrhage within a closed space such as the broad ligament or uterine wall in a
mare with colic or pale mucus membranes, can be confirmed by per rectum
palpation and ultrasonography; in such cases, it is hoped that a clot will form and
staunch the bleeding. It is not common to attempt to ligate the offending vessel and,
instead, treatment is supportive and concentrates on pain relief, blood transfusion if
the packed cell volume drops rapidly or is below 12 and falling, and maintaining the
mare in a quiet environment in the hope that the distended broad ligament does not
rupture or that the haemorrhage does not dissect out through the tissues of the
uterus and vagina. Further circulatory support is provided only if absolutely
necessary, because while expanding the circulatory volume and raising the blood
pressure may aid perfusion and oxygenation, they can also interfere with clot
formation. Anti-fibrinolytic drugs such as aminocaproic acid are sometimes
recommended to assist clot stabilisation, but very little is known about their efficacy
in horses.
Conclusions
Mares occasionally present with mild colic or discomfort in late gestation as a result
discomfort due to fetal movements or uterine contractions that prepare the uterine
smooth muscles for their role in labour. If discomfort is more severe or does not
resolve fairly rapidly, a more extensive investigation is required to rule out GI
complications, to investigate fetal viability and rule out abnormalities of the placenta,
fetus or uterine contents that may indicate imminent abortion. In late gestation
mares, a rectal examination is required to rule out the possibility of uterine torsion
and to assess the condition of the broad ligaments. Examination of the ventral
abdominal wall as a potential source of pain is also recommended. Investigation of
gross mammary secretion appearance and electrolyte concentrations and pH can
help indicate whether the mare is close to parturition or is threatening to abort.
References
Spoormakers TJ, Graat EA, Ter Braake F, Stout TA, Bergman HJ (2015) Mare and foal survival and subsequent fertility of
mares treated for uterine torsion. Equine Vet J. doi: 10.1111/evj.12418. [Epub ahead of print]
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
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