One of the problems that can occur when a ewe is lambing is that the cervix (the muscular ring at the entrance to the womb) doesn't relax and expand fully to allow the passage of the lamb(s), so the lamb(s) can't get out. This is "ringwomb".
In true ringwomb, the cervix cannot be distended and there is no treatment other than a Caesarean operation.
"True" ringwomb should not be confused with "false" ringwomb, a condition in which the cervix has become partly dilated. With false ringwomb, careful patient manual stretching of the cervix can sometimes cause it to relax and expand to allow the lamb(s) to be delivered.
With true ringwomb, the ewe may have been straining for hours with no progress being made, although usually, the membranes protrude from the vulva. Sometimes there is no real sign of straining. On manual examination, only one or two fingers can be passed through the cervix into the womb, even though the two forefeet and head of the lamb may be presented quite normally just inside the cervix. The outside edge of the cervix usually feels hard and unyielding, almost like an extended rubber ring – hence the name 'ringwomb‛.
The cervix is made up of muscles pursed together around the uterine entrance. In normal labour, these muscles gradually relax and open up when pressure is exerted by the fluid-filled sac and the lamb from inside. This pressure is caused by the contractions of the muscles of the uterine wall pushing the head of the lamb against the muscles at the top of the cervix.
In 'true' ringwomb, there is no treatment other than a Caesarean operation to save the ewe and lambs, or euthanasia of the ewe to save the lambs. Caesareans are usually successful. If no action is taken, the lamb eventually dies when its placenta separates from the uterine wall and its blood supply is cut off. In a few cases the ewe aborts the rotten lamb and then she requires veterinary treatment or she will develop septicaemia (blood poisoning) and die.
The cause of 'true' ringwomb is not known for certain, but some cases may have a genetic component, and some cases may be the result of scarring of the cervix as a result of a previous traumatic lambing. Some farms certainly experience more cases than others. It is wise to cull any ewes that have survived the condition.
Many cases of 'false' ringwomb are likely to be the result of premature intervention by the shepherd. It takes time (up to an hour) for the cervix to dilate fully during the lambing process. Earlier (premature) interference may mean that further dilation doesn't proceed normally. Some cases of false ringwomb may result when the lamb is in the wrong position for delivery so that the head and forefeet don't exert normal pressure on the cervix to open it.
If the cervix is not fully open, and if it is not scarred, an experienced shepherd or a veterinarian can, by gentle stretching of the cervix using the bunched fingers of a clean lubricated hand for up to 45 minutes, gradually ease it open sufficiently to allow delivery. However, the lamb(s) may be weak.
Do not attempt to pull the lamb out through a cervix that is only partly open, even if you can put a few fingers through and feel a lamb's feet or nose. If the cervix is not fully relaxed you could cause fatal injuries to the ewe leading to peritonitis and prolapse of the uterus/vagina.
In true ringwomb and in many cases of false ringwomb, the best solution for the lifestyle farmer is to call your vet. Your vet may decide that a Caesarean is needed to save the ewe and lambs. Alternatively, the ewe could be euthanased and the lambs salvaged immediately for fostering.
Tips for manual examination of the birth canal
- Before doing a manual examination of the birth canal, trim off any dags or dirty wool around the back end of the ewe.
- Make sure your nails are short with no jagged edges, remove rings, watches and bracelets and wash your hands thoroughly in warm soapy water.
- Wear surgical gloves if possible.
- It can help to put the ewe on the back of a truck or trailer deck so that her back end is at an easier height for any manipulations that are required and there will be less temptation to rush.
- Bunch your fingers and insert your hand carefully into the vagina.
- Coat your hand and arm with plenty of lubricants (such as veterinary lubricant or LUX soap flakes and warm water). Pass one or two fingers through the partly open cervix and exert gentle pressure on the inside – particularly at the top – repeatedly relubricating or filling the vagina and cervix with lubricant or soap flakes and warm water. Work away quietly and gently for up to half an hour or even longer if progress is being made. Many cervixes eventually relax and open as a result of this simple internal gentle digital pressure. Keep moving your fingers around the inner ring and stop each time the ewe strains. If no progress is made after 30 minutes, then consider euthanasia of the ewe or call your vet for a Caesarean section.
Ringwomb can also occur in goats but it seems that 'true' ringwomb is much less common in goats than in sheep but 'false' ringwomb may still be a problem as in sheep.