Equis ISSN 2398-2977

Fecal occult blood test

Contributor(s): Prof Derek Knottenbelt, Ruth Morgan, Vetstream Ltd


  • To determine presence of alimentary tract bleeding and gastrointestinal ulceration.
  • There are several types of test: the basic application of urine dipstick provides a rudimentary indication, but has not been validated; there are also commercially available tests working either by antibody detection mechanisms or by guaiac acid.
  • Guaiac acid works by binding hemoglobin which induces a color change, this is the fecal occult blood test used in humans.
  • The most commonly used commercial product in horses is SUCCEED® . This system is an antibody detection system able to detect albumin and hemoglobin.
  • Extensive validation of the tests in horses has not been carried out and there is limited data available.
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  • The fecal occult blood test can be used to aid in diagnosis of gastrointestinal bleeding.


  • A non-invasive test which may give an indication of bleeding within the gastrointestinal tract specifically gastric ulceration or colonic ulceration which are the most common sources of bleeding.
  • A guaiac acid fecal occult blood test (gFOBT) has been found to have good sensitivity and specificity when results were confirmed at post mortem. It was found to be 65% accurate for diagnosing the presence of either gastric or colonic ulcers. False negatives are common though.
  • The SUCCEED® equine fecal blood test is based on 2 antibody tests:
    • Test A utilizes antibodies to equine albumin and is said to indicate bleeding in the hindgut.
    • Test H utilizes antibodies to equine hemoglobin and this is said to be indicative of bleeding from anywhere in the GI tract.


  • If only the fecal sample is used intermittent bleeding may go undiagnosed.
  • False negatives are common.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Pellkegrini F L (2005) Results of a large-scale necroscopic study of equine colonic ulcers. J Equine Vet Sci 25 (3), 113-117 VetMedResource.