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 The SUCCEED® FBT has been thoroughly tested to ensure it meets our high standards — and yours.
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The SUCCEED® Equine Fecal Blood Test™ is the result of years of development. During that time, the SUCCEED® FBT has been thoroughly tested by Freedom Health to ensure it meets our high standards — and yours. Here's a summary of the results of much of this research.
The SUCCEED® Equine Fecal Blood Test™ is based on two simple concepts. The first is that albumin and hemoglobin are good indicators of digestive tract injury, and can help differentiate foregut from hindgut sources of that injury. The second is that antibodies may be developed that are highly sensitive and specific to equine albumin and hemoglobin. Multiple tests, both in vitro and in vivo, were completed to assess the accuracy of the antibodies, as detailed below.
The FBT concept works as a differential diagnostic aid because enzymes in the stomach and duodenum are known to completely digest albumin, while hemoglobin is resistant to these enzymes and the bacteria in the colon. Thus, a positive test of albumin in equine feces must have originated from a source caudal to the common bile duct in the proximal portion of the small intestine. To confirm this, equine blood was introduced into the gastric cannulae of two experimental horses. Polyclonal antibodies to equine hemoglobin (Hg) and albumin (Ab) were used to test the feces over an 18 hour period. The results show a slow decay of hemoglobin detected in the manure samples, while a consistently low level of albumin was detected over that same period.
Figure 1 — Results from an Averaged Time-Course Assay on 2 Horses
Download the study (PDF).
The antibodies used in the two parts of the SUCCEED® FBT – Test A and Test H – were evaluated by introducing equine blood at varying concentrations into a solution of water and rabbit fecal matter. The FBT antibodies have the following detection limits at a 95% confidence level:
Figure 2 — Minimal Detection Levels of FBT Antibodies
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Test A |
Test H |
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Antibody |
Antibody |
| Detection Limit: |
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8 ppm |
7 ppm |
The antibodies utilized in the SUCCEED® FBT are supersensitive. As such, they can detect the presence of albumin and hemoglobin in manure that would likely occur naturally in a healthy horse. Therefore, the sensitivity level of the SUCCEED® FBT had to be set at a level above this “baseline.”
An earlier study utilizing radio-labeled hemoglobin indicated that a normal, healthy horse loses 1-2 mL of blood in feces, averaging 12 kg of fecal matter per day. Given the hemoglobin-to-blood ratio of 125-150 mg/g, the baseline of hemoglobin loss in a horse is in the range of 125-300 mg in daily fecal matter output. Using the higher end of this range, the sensitivity of the SUCCEED® FBT was set at 750 mg, or 2-1/2 times the baseline at the maximum end of the “normal” range.
The SUCCEED® FBT is an accurate predictor of digestive tract injury. This was assessed in a necroscopic study in August 2007. In this study, test results from fecal samples of 86 euthanized horses were compared with visual observation of gastric and colonic tissue samples. Results are as follows. Here, diagnostic sensitivity is defined as true positives / true positives + false negatives, and specificity is defined as true negatives / true negatives + false positives. The positive predictive value indicates the probability that a positive test predicts a genuine underlying problem (true positives / all positives). Results for Test A are compared with colonic injury of grade 1 or higher, applying the standard EGUS grading scale. Results for Test H are compared with either gastric or colonic injury of grade 2 or greater.
For more details, download the complete technical abstract (PDF).
The extent to which the SUCCEED® FBT cross-reacts with the blood of species other than horses was assessed. This was done by measuring minimum detectable concentration limits when introducing blood from various species into the samples.
Figure 4 — Minimum Detectable Limit of FBT Antibodies with Non-equine Species Blood
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| Sample |
Test A |
Test H |
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| Rabbit |
ND |
ND |
| Goat |
ND |
ND |
| Sheep |
ND |
ND |
| Cow |
ND |
ND |
| Pig |
ND |
ND |
| Camelid |
ND |
ND |
| (ND = No detection at any concentration.) |
As shown in Figure 4, Tests A and H are both highly specific to equine blood.
Based on necroscopic analysis of equine subjects, the following incidence levels of various disease states were observed in two studies:
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