Colitis-X in Horses

3 min read


Colitis-X is a serious intestinal condition that is not very well understood. Often fatal, its cause is unknown although it appears to affect horses under stress such as stress caused by transport or surgery. This is often a catch-all term used when a more definitive diagnosis for the cause of the diarrhea has not been found.


This condition progresses extremely fast, with severe watery diarrhea being the most obvious clinical sign. The fluid loss from the diarrhea is so severe that dehydration quickly sets in, causing hypovolemic shock and death. Emergency treatment may be attempted, but it is rarely successful. The death rate for this condition approaches 100%.


Symptoms and Types


  • Severe depression
  • Recumbency
  • Dark red to purple mucous membranes (gums)
  • Rapid heartbeat
  • High temperature/fever followed shortly by abnormally low temperature
  • Severe watery diarrhea
  • Mucous in stool
  • Dehydration
  • Pain in abdomen
  • Hypovolemic shock
  • Death (usually follows shock from sudden drop in temperature and loss of body fluids)




  • Specific cause is currently unknown
  • Linked to high stress such as transport or extensive surgery
  • Some cases have been reported to follow treatment with the antibiotics tetracycline and lincomycin.
  • May also be linked to peracute Salmonella or Clostridial bacterial infections




Colitis-X is a diagnosis of exclusion, meaning it is used when no other cause for the severe diarrhea can be found. Given the rapid progression of this disease, it is extremely challenging to institute treatment and determine a diagnosis before the death of the horse.


Necropsy (animal autopsy) can sometimes aid in the diagnosis of this condition, as all cases show similar damage to the lining of the intestines.