term. Grade IIb is characterized by more widespread inflammatory foci or
fibrosis, and the probability of producing a live foal drops to 10-50%. A Grade
III endometrium is characterized by extensive fibrosis (multiple layers of
fibroblasts around glands), formation of gland nests, irregular gland
distribution and loss of the epitehlium. Although, with careful management,
grade III mares can be got pregnant they have a < 10% likelihood of carrying
that pregnancy to term. Unfortunately, endometrial degeneration is largely
untreatable but, at least for type IIa and b mares, careful management at the
time of insemination and treatment of any specific infections will reduce the
significance of the inflammatory changes and thereby improve the prognosis.
Hysteroscopy
Hysteroscopy is not commonly indicated, but can be useful in mares with a
history of dystocia, caesarian section, intra-uterine treatment with irritant
solutions, unexplained infertility of long duration, abnormal ultrasonographic
appearance or unusual fluid accumulations where there is a possibility of
intrauterine adhesions. In addition, hysteroscopy can be used to visualize and
remove intra-lumenal cysts (using an Nd:YAG laser or diathermy loop), if they
are thought to be large or numerous enough to cause problems, and
intrauterine foreign bodies (e.g. tip of a culture swab, glass ball used to treat
behavioural problems). Hysteroscopy is best performed in dioestrus because
the cervix is closed and best able to retain the air that is needed to inflate the
uterus for good visualization. The mare should be sedated since some react
violently to uterine inflation. The endoscope should be ‘steered’ to the tip of
each horn and the normality of the utero-tubal junction, where the oviduct
enters the uterus, should be examined. Any damage to this structure could be
a reason for infertility while failure to locate a UTJ may indicate presence of a
large adhesion. The rest of the uterus should then be checked as the scope is
brought back down each horn. Like cysts, intra-uterine adhesions should be
treated by blood-free surgery (i.e. laser or diathermy), although an
endometrial biopsy should also be taken to help provide a prognosis for
subsequent fertility. A biopsy can be taken under visual control and this is
particularly useful when areas of the endometrium look abnormal. Uterine
tumours do occur in the mare (esp. leiomyomas) but are rare.
Laparoscopy
The utility of laparoscopy for the investigation or treatment of sub-fertility is
something that has become more common in recent years, following the
demonstration that chronic subfertility in some mares can be rectified by
treating the oviducts with PGE2 gel that induces relaxation and allows
accumulations of degenerating oocytes and gelatinized follicular fluid that may
occlude the oviductal lumen to be discharged (Allen et al, 2006).
Conclusions
Over the last 20-30 years, there has been an appreciabl e increase in our
understanding of what is and what is not normal in the broodmare and when
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February
2016
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London
Convention
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East
London,
South
Africa
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