Reading the results of a SUCCEED FBT is similar to reading a pregnancy test. A control line indicates that the test is working, and a second line – no matter how faint – indicates a positive result for either albumin or hemoglobin.
Observe results after applying the solution to each of the two sample wells on the cassette.
- If a Control line does not appear within 15 minutes (at the CTL point on the cassette) that test result is invalid. The test must then be repeated with a new SUCCEED Equine Fecal Blood Test.
- If only a control line appears on either strip, that test is NEGATIVE. NOTE: only a complete line is a meaningful result.
- If both the Control and Test lines appear on either window (Test A or H), this indicates a POSITIVE test result. Even if the test line is faint, the test is POSITIVE.
- Do not read test results after 15 minutes.
How to Interpret Positive and Negative FBT™ Results
The following chart summarizes the meaning of a positive and/or negative test results across SUCCEED FBT tests A and H.
- Negative A, Negative H = no GI tract issue detected.
- Positive A, Negative H = GI tract issue detected in hindgut.
- Negative A, Positive H = GI tract issue detected in foregut.
- Positive A, Positive H = GI tract issue in hindgut. Foregut issue also possible.
Note that Test A uses an antibody for albumin, which typically breaks down in digestion, particularly when exposed to digestive enzymes in the proximal portion of the small intestine, relative to the common bile duct. Thus a positive Test A will indicate injury producing albumin at a location caudal to the duodenum. While such injury is most likely going to occur in the hindgut (particularly the colon), veterinarians should note that intestinal sources are still possible.
Also, because albumin may be present at the site of low-grade injury absent whole blood, a positive Test A may result from a low-grade lesion in the hindgut (i.e.,.a “weeping” lesion), such as may occur with heavy parasitism or disseminated grade 1 colonic ulcers.
Test H uses an antibody for hemoglobin, which is more resistant to the enzymes, acids and other actions of the GI tract. This means hemoglobin may be present in the feces from sources anywhere in the GI tract. Thus a positive Test H, with negative Test A, will indicate foregut injury where active bleeding is occurring. You will not obtain a positive result from either Test A or H when a horse has a foregut lesion equivalent to a grade 1 gastric ulcer, where whole blood loss does not occur.
While the SUCCEED FBT results are not difficult to interpret, understanding how they fit into a complete and accurate diagnosis requires the specialized knowledge of a veterinary practitioner. The results of the SUCCEED Equine Fecal Blood Test are just one helpful tool in your diagnostic arsenal, providing direction for what steps to take next.
Here are examples of factors to keep in mind throughout the diagnostic process, in addition to FBT results.