ThePigSite Pig Health
Prolapse of the RectumSee also chapter 9.
(343) This is not uncommon in sows and occasionally outbreaks occur in herds. Whilst the exact mechanisms are not fully understood the following should be considered as contributory to the problem.
- A prolapse may occur following oestrus, associated with levels of oestrogenic hormones that are present at this time.
- It maybe associated with constipation.
- Penetration of the rectum at mating is a common cause with prolapse occurring 24 to 48 hours later.
- Cases develop if sows are confined in stalls or tethers where there is an excessive slope towards the back of the floor. Up to 8 % of sows have been affected where sows are confined to stalls or tethers with sloping floors to the rear.
- Rectal prolapses are seen occasionally in sow stalls or farrowing crates where the retaining gate at the back consists of parallel bars. If these are of such a height that the sow can sit or rest with the tail over the back, pressure is placed on the anal sphincter. This causes a partial relaxation of the sphincter itself, poor circulation, swelling and ultimately the sow strains to prolapse.
- A small lying area with a step down to the defecating area causes increased abdominal pressure if the sows lay over it. This predisposes to prolapse.
- Prolapsed rectum may occur whenever there is an increase in abdominal pressure.
- Abnormal fermentation in the gut and the production of gas in the large bowel may predispose. In such cases the components of the feed and the method of feeding should be investigated.
- Mouldy feeds or straw can be important causes of rectal prolapses due the present of mycotoxins.
- Low fibre diets can lead to constipation and rectal prolapse.
- When environmental temperatures drop, sows that are loose-housed group together to keep warm, thus increasing abdominal pressure.
- A water shortage may predispose.
- There is no evidence to suggest that genetic factors have a part to play in the disease.
At the onset, the red coloured mucosa of the rectum protrudes from the anal sphincter and then may return on its own. After a short period however it remains to the exterior and becomes swollen and filled with fluid. It is prone to damage and haemorrhage and where sows are loose housed cannibalism often results with evidence of blood on the skin.