Bearings are a function of internal pressure and vaginal wall integrity. The internal pressure changes come from:
- Abdominal fat
That's why triplets have the greatest risk (more uterus volume). That's why gorge feeding, feed changes and bulky feed can be a risk: the rumen expands rapidly and produces more gas when not adjusted. That's why sitting down for long periods, and high water content feed (fodderbeet and swedes) and salt can be a risk: the bladder gets bigger. That's why weight gain post mating is a risk: increase in abdominal fat. That's why low calcium levels are a risk: smooth muscle not as toned (and why Vitamin D might help).
For these reasons that why exercise throughout the day, consistent rumen fill and feeding levels are protective against bearings. However we can't prevent them all. Successful treatment of bearings relies on early detection, expression of the bladder, gentle and clean replacement and effective retention. Exposure time is a prognostic indicator of success. Early treatment involves thoroughly cleaning the vagina and gently lifting it to allow the ewe to urinate. Following prolapse, ewes are unable to urinate due to a kink in the urethra. Lubricant should always be used and gentle even pressure applied to replace the prolapse. Replacing the bearing is easiest when the back end of the ewe is elevated. Retention of the bearing can be by external pressure from a number of options including internal bearing retainers, harnesses or a purse string suture around the vulva with umbilical tape or suture. All ewes should be prophylactically covered with antibiotics. Suitable choices are a Penicillin of Tetracycline derivative.