• Intrauterine glass marble
This protocol is simple and performed by putting a 25 to 35 mm sterile glass marble
intra-uterine 24 to 48 h post ovulation when the cervix is still maximally relaxed. Prior
to the procedure the perineum of the mare is thoroughly washed, a sterile sleeve is
then used with a small amount of sterile lubricant (Priority Care®) applied to the back
of the hand, to facilitate passage of the hand though the vestibule and the vagina.
The marble is manually carried through the vagina towards the entrance of the
caudal os of the cervix. Using a finger, the marble is then pushed forward through
the external os of the cervix into the lumen of the caudal part of the uterine body.
After removing the hand from the vagina, the marble is then transrectally pushed
forward towards the uterine bifurcation. At the end of the procedure, the uterus can
be infused with antibiotics if there is concern of contamination of the uterus during
the manipulation. Glass balls can be autoclaved at a temperature of 121◦ C (250◦ F)
and a pressure of 1.1 bar (16 psi) and thereafter re-used. The aim of this method is
to prolong the CL function in the mare as the glass ball imitates the embryo. A study
by Nie et al. in 2003 (30) showed a prolonged CL function in 39% of the mares that
retained the glass marble (50% of the mares expelled the 25-mm marble). Despite
the fact that it did not work in the majority of the mares, which was a significant
disadvantage, in the other 50% of the mares a luteal function was maintained for
approximately 90 days. In the early stage no immediate detrimental effect of the
glass ball on the uterus was reported. Although the marble therapy is not expensive,
one has to consider some serious disadvantages when used long-term in the uterine
lumen of a mare. Spontaneous fragmentation of the glass ball in the uterus of a mare
and pyometra were the most severe complications reported very recently by Dirk
Vanderwall (JAVMA of augustus 2015). Clinical signs could include vulvar discharge,
signs of urogenital discomfort, and chronic, intermittent colic. Some mares carried
two glass balls in the uterine lumen, presumably as a result of insertion of a second
glass ball without knowledge of the first or on the basis of an assumption that the first
had been spontaneously expelled. Clinicians would be advised to carefully check –
by trans rectal palpation or ultra sound exam- for intrauterine glass balls in mares
that have been retired from performance activities so that any intrauterine glass ball
can be removed.
Removal of the glass marble is best performed when the mare is in peak oestrus and
normally does not need tranquillisation. Mares with pendulous horns present the
most difficulty. If the cervix is not fully dilated, a second gloved hand is taken per
vagina to the caudal cervical os. That way the glass marble is retrieved from the
uterine lumen. Attempts to breed mares with intrauterine glass marble have been
described and there are anecdotal reports of mares becoming pregnant despite of
the presence of the glass marble in the uterine lumen with subsequent compromise
and loss of the pregnancy. Glass marbles that have spontaneously fragmented in the
uterine lumen leaving behind glass shards could lead to impaired fertility; therefore,
should be removed if not necessary any more.
Rivera del Alamo et al. (31) replaced the glass ball by a 20-mm water-filled
polypropylene ball, and concluded that the corpora luteal function was extended in
75% of the cases with an average duration of 57 days. Small accumulations of
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
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