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13 July, 1999
Bearings (prolapses of the vagina) in ewes can be a problem every year as
lambing approaches, even on the best managed farms. A senior animal welfare adviser for
MAF's Enforcement Unit, David Barbour, said dealing with bearings means careful
scrutiny of flocks several times a day as ewes approach lambing, with prompt treatment of
The cause of bearings is complex, Mr Barbour said, but one major factor
was increased pressure in the abdomen. The reasons for this included a womb full of lambs,
a full rumen, a full bladder and a lot of abdominal fat.
Mr Barbour said that in the fifth and the last month of pregnancy, it is
not wise to try to prevent bearings by trying to reduce ewe body weights. "This will
only predispose ewes to metabolic diseases such as sleepy sickness."
Other factors include slackness of the ligaments around the birth canal,
sometimes associated with poor nutrition, so although it is often fat ewes that prolapse,
ewes in lean condition are susceptible too. It has been suggested that low magnesium
status and possibly low calcium status may be involved, and another theory is that
selection for ease of lambing has resulted in ewes with a generous birth canal which is
more likely to prolapse.
Treatment of prolapsed ewes always involves replacing and retaining the
bearing, but in advanced cases Mr Barbour said the most humane option was euthanasia.
"Farmers who are unsure what to do in the event of their ewes developing bearings
should consult a veterinarian at the earliest opportunity."
Treatment involves cleaning the prolapsed mass very carefully and gently
replacing it, then holding it in place. "The bearing is very easily damaged, and
infections will occur unless great care is taken to clean and gently press it back into
place without causing damage."
Holding the prolapse up to allow the bladder to empty before trying to
replace it is important, he said. Facing the ewe downhill or elevating her hind end aids
replacement. Lubricant helps greatly. Antibiotic injections are necessary to prevent
serious womb infections.
Once a ewe has prolapsed it is very likely that the bearing will be pushed
out again unless it is somehow retained, because the damage done to the vagina during
prolapse causes irritation which in turn causes straining. The gentlest method of
retaining prolapses involves tying wool over the vulva.
Another simple and often effective technique involves using a length of
baling twine placed in front of the pelvis bones (pin bones), brought down the sides of
the ewe, inside each hind leg, crossed over the vulva and tied back onto the string where
it string goes over the ewe's back in front of the pin bones. The string should be
sufficiently tight to prevent the prolapse from recurring.
Commercially-available bearing retainers can be used. Like the tied wool
and simple string techniques, these have the advantage that the ewe can lamb past them.
However they should be removed as soon as lambing begins.
There are other methods of retaining bearings. Some of these involve
stitching or clipping the vulva closed. This can be effective if carried out skilfully and
hygienically, and if the stitches or clips are removed at lambing.
David Barbour, MAF Enforcement Unit, P O Box 271, Rangiora
Phone 021 337 128 Fax 03 313 0045.