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Prolapse of the Rectum

This is not uncommon in sows. It is a widespread condition occurring in growing pigs from 8 to 20 weeks of age. The onset is sudden.


Weaners & Growers
  • The size of the prolapse varies from 10 to 80mm and if small it will often revert into the rectum spontaneously.
  • In most cases however the prolapse remains out becomes swollen and filled with fluid.
  • It is also prone to damage with haemorrhage.
  • Cannibalism often results by other pigs in the pen as shown by blood on the noses of the offending pigs and on the flanks of others.
  • Blown up abdomen seen in pigs 2 - 4 weeks after prolapse (rectal stricture).
  • Pale pigs due to haemorrhage.
  • Constipation.
  • Sometimes death.
  • Rare.
  • At the onset, the red coloured mucosa of the rectum protrudes from the anal sphincter.
  • May return on its own or remain to the exterior, become swollen and filled with fluid.
  • It is prone to damage, haemorrhage and cannibalism.
  • Pale pigs due to haemorrhage.
  • Blood in faeces.

Causes / Contributing factors

The exact mechanisms are not understood but the following should be considered as contributory factors.
  • Prolapses which occur after oestrus in the sow may be related to sex hormone levels.
  • Penetration of the rectum at mating may result in prolapse 24-48 hours later.
  • Stalls or tethers with an excessive slope of the floor towards the back.
  • Sow stalls or farrowing crates with the back retaining gate consisting of parallel bars seem to predispose. If the sow can rest with the tail over the back gait, pressure is placed on the anus. This causes a partial relaxation of the sphincter, poor circulation and swelling. The sow strains and prolapses.
  • Genetic factors do not appear to have a part to play in this condition.
  • Trauma
  • Tail docking - docking tails too short can damage the nerve supply to the anal ring leading to a relaxation of the anal sphincter.
  • The fundamental cause is an increase in abdominal pressure which forces the rectum to the exterior and a swelling of the mucous lining and then straining.
The following may be considered as causal or contributory particularly in growers.
  • Diarrhoea - excessive straining.
  • Respiratory disease - excessive coughing increasing abdominal pressure.
  • Colitis - abnormal fermentation occurs in the large bowel with the production of excessive gas increasing abdominal pressure.
  • In cold weather the incidence of rectal prolapses increases. This is associated with low house temperatures and the tendency of pigs to huddle together, thus increasing abdominal pressure.
  • Wet conditions and slippery floors, particularly those with no bedding, increase abdominal pressure.
  • If stocking densities reach the level whereby pigs cannot lay out on their sides across the pen the incidence may increase. It is often related to specific houses on the farm.
  • Nutrition:
    • Ad lib feeding - Feeding pigs to appetite results in continual heavy gut fill and indigestion. There is then a tendency for abnormal fermentation in the large bowel because undigested components of the feed arrive in greater amounts.
    • High density diets and in particular lysine levels increase growth rates and outbreaks may often subside either by a change to restricted feeding or using a lower energy / lysine diet.
    • Diets high in starch may predispose to prolapse - Try adding 2-4% grass meal to the diet.
    • The presence of mycotoxins in feed - If there is a problem make sure that the bins have been well cleaned out. Examine the cereal sources.
    • Change of diet - By studying the timing of the problem it is sometimes possible to identify rectal prolapses not only with a change of diet but also a change of housing.
  • Prolapses may occur with constipation e.g. from feeding a low fibre diet, shortage of water.


This is based on the clinical picture.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.