Compared to other farm species, the pig appears to be
particularly vulnerable to prolapse of the rectal tissue through
the anus, which can be seen in any age group from as early as 1-2
days old up to adults. The fundamental cause of the prolapse
is an increase in abdominal pressure, forcing a breakdown in the
weak muscular support mechanism of the pelvis, which normally
retains the rectum in place. There may well be both breed and
gender differences in the vulnerability of individuals to prolapse
Fig 1: A typical rectal prolapse in a
Fig 2: Rectal prolapse in a sow post
Fig 3: Rectal stricture - a common sequel to rectal
Fig 4: Massive distension of the large intestine in
association with stricture
Fig 5: Scar tissue forming a stricture can extend
well into the large intestine
Causes of Prolapse
The following list provides an outline of the most common causes
of prolapse, as seen in commercial pig farms:-
1) Diarrhoea or dysentery - particularly associated with large
intestine inflammation that may include rectal inflammation (e.g.
Salmonella, Swine Fever, Swine Dysentery).
2) Constipation most likely to be seen in the adult close to
3) Parturition - as a result of excessive straining.
4) Water shortage - leading to reduce water content of the
faeces and increase straining to pass.
5) Medicines. Certain antibiotics (Tylosin, Lincocin) have
been associated with oedema (swelling) of the lining of the rectum
and subsequent prolapse. This is most likely seen with high
6) Toxins. Some mycotoxins from feed or straw can be
associated with rectal swelling and straining.
7) Rectal damage e.g. as a result of boars riding each
8) Coughing. The process of coughing causes an increase in
abdominal pressure and, in some cases, this may be sufficient to
push out the rectum. Many animals will expel faeces as they
cough and the rectal lining will penetrate through the anus.
In extreme cases, it does not return and remains prolapsed.
9) Fast growth. Prolapsing can often be a problem in fast
growing pigs, particularly from 30-60kg on very high-density
Variable temperatures. Pigs have a poor ability to control
their body temperature and tend to be adversely affected by
variation in the ambient temperature and prone to chilling.
The consequence is huddling and piling on top of one another.
If a pig then coughs while another is lying on top of it, the
abdominal pressure will be even higher than normal and the only
place that the pressure can be relieved is at the anus.
Once a prolapse has occurred, a number of events may
1) It rapidly returns into the anus.
2) It remains outside the anus and, due to the constrictive
effect on blood and fluid drainage, it generally swells up.
It is thus easily damaged by trauma on pen divisions, feeders
3) It is eaten by other pigs in the pen. It is not
uncommon to find blood in a pen and around the mouths of pigs but
with no obvious prolapse in any other animals i.e. the prolapse
will have been completely chewed off.
Long term consequences may be:-
a) No effect - particularly if the prolapse returns without
b) Slow dying off of the prolapsed material over several weeks
with the chances of secondary infection arising from rotting
c) Rectal stricture. The prolapse resolves but the scar
tissue left forms a ring of slowly constricting tissue that
eventually blocks the rectum leading to a "blown up" pig (Fig
3). Such animals require euthanasia.
Rectal stricture is a common condition in growing pigs in which
scar tissue forms a ring inside the terminal rectum which slowly
closes, obstructing the bowel and preventing defecation.
The result is that faecal material accumulates in the
colon,caecum and rectum (large intestine) leading to distension of
the abdomen (fig 3). Body condition is lost and the pig
ultimately becomes gaunt and hairy. Occasionally the skin may
take on a yellow tint as bile, which would normally be excreted, is
reabsorbed. Death is a natural end point but humane
destruction will be required before this. Affected pigs are
not suitable for slaughter for human consumption.
At post mortem examination the large intestine will be
hugely distended and inflamed (fig 4) and dissection of the rectum
from within the pelvis will reveal a ring or band of scar tissue -
sometimes extending well up into the colon - obstructing the gut
(fig 5). Frequently, micro-abscesses will be present around
If the stricture starts adjacent to the anus it is reasonable to
assume that a prolapse previously bitten off by another pig was the
start point of the stricture. However, in many cases there is
a section of normal mucosa between the anus and the stricture,
suggesting that a prolapse had not been the root cause. This
area of the rectum has a poor blood supply and the primary damage
leading to scaring may be due to either trauma (e.g. penile
penetration) or inflammation/infection either locally in the rectum
or via the blood supply. Salmonella sp, Haemophilus parasuis
and Strep suis have been implicated.
Where strictures occur not associated with
prolapses, it is essential to establish the primary cause and
address that to prevent further causes.
If strictures can be detected early, before the rectum is
completely blocked, it may be possible to gently stretch the
stricture by digital manipulation to allow the pig to continue to
defecate. Great care is needed not to rupture the rectum.
On some farms, losses resulting from rectal strictures can
account for one percentage point of production (i.e. 5-10% of all
deaths in the feeding herd).
Any animal noticed with a prolapsed rectum should be isolated
away from other pigs. If it is of slaughter weight, it can
immediately be despatched for slaughter with a food chain
information declaration. It should be transported in
If swollen but undamaged, it may be possible to replace the
prolapse by sprinkling sugar or salt on it, leaving it 30 minutes
and then gently pushing it back in. The osmotic effects of
the salt/sugar draws out the fluid and shrinks the prolapse.
It may be necessary to place a purse string suture around the
anus to retain the rectum once replaced.
In a large animal (sow), a rubber washing up glove placed over
an undamaged prolapse may exert enough pressure to shrink the
tissue and return it inside the rectum.
Where a prolapse is damaged and clearly not in a state to
replace, it must be amputated. The easiest way to achieve
this is to insert a pipe (1" diameter for a growing pig, 1 ½" for
sows) into the prolapse and tie a ligature around the prolapse
baring down onto the pipe. It is necessary to tie the pipe in
with the loose ends of the ligature. This will cut the blood
supply to the prolapsed material and allow it to dry up and drop
off, usually in less than 7 days, although it may be necessary to
re-tie the ligature after 3-4 days as the tissue shrinks. If
corrugated pipe is available (e.g. electrical conduit), heavy-duty
rubber bands or even lamb elastrator rings can be used as a
In all cases, antibiotic cover should be provided.
Where damage is so great that intestinal tissue prolapses
through the open wound immediate humane slaughter is
required. Similarly where a rectal stricture has resulted,
the animal will lose body condition whilst the abdomen continues to
swell and reabsorbtion of bile in the gut produces clinical
jaundice. Such animals are practically untreatable and
unmarketable and must be humanely destroyed.
Clearly, prevention of rectal prolapses rests in being able to
identify and correct the cause of the problem.
It is extremely difficult to quantify the financial losses
associated with rectal prolapse as in most cases it is underlying
disease which precipitates the prolapse and it is the cost of the
disease itself, which is most important.
However, where there is no underlying disease a prolapse in
growing pigs is the result of high growth rates it is possible to
give examples. A farm typically affected can lose 2% of all
growing pigs as a result of prolapse/stricture at an average cost
of say £80/head (including lost profit opportunity).
Therefore for a 500-sow breeder feeder farm over a year this could
add up to a loss of 230 growing pigs worth £18,400/year. This
cost would then have to be offset by the cost of slowing growth to
prevent prolapse. For example if 50gm/day daily live weight
gain was sacrificed between 30 and 100kg this would add 6 days to
reach slaughter weight; with additional feed and facility costs
this would incur a cost of at least £1/pig. On the model 500
sow breeder feeder farm this would add costs of approximately
£11,000/yr. (If space does not permit retention for this extra 6
days then up to 3kg would be lost from the carcass weight and the
losses would triple). Of course, the absolute financial cost
of incurring/preventing rectal prolapse would have to be viewed in
the light of the welfare cost to the animals affected