Dear Amy:
 
>Does anyone have any ideas on what causes this.  I have a 4 1/2 year old
>who periodically has this problem, it always fixes itself pretty quickly.
>His poops are fine and everything seems normal.
 
There is no one cause to prolapsed recutm.  the common denominator in all
cases is straining - the pushing causes a loosening or breakdown of the
connections in the preineum, so the rectum can actually protrude through
the anus.  When it does, irritation and swelling of the mucosa prevents it
from retracting back into the body.
 
What causes the straining - well, that has many causes, and they can be
very diffiuclt to identify - we actually make very few diagnoses of the
root cause of prolapsed rectums.  Anything that causes diarrhea can cause
straining.  Doesn't seem logical, does it - watery feces should just flow
out without any problem.  But the body actually does strain during
diarrhea, and often strains mightily - trying to find some bulk to push
against during elimination.  So anything that causes diarrhea can cause a
prolapsed rectum.  Animals who have previously had prolapsed rectums as
adults tend to have recurrences with increasing prevalence.  Prolapses are
not uncommon in young pet store kits which often have rapid food changes,
viral disease, or parasites, and if the originating cause is treated, the
prolapses usually do not return.
 
With kindest regards,
Bruce Williams, dVM
[Posted in FML issue 3233]