What test is used at Vita-Tech to detect the presence of blood in the stool?

Vita-Tech uses Hematest Reagent Tablets, which is a peroxidase based test system. This is a chemical test that utilizes the peroxidase-like activity of hemoglobin to detect the presence of blood on or in fecal material at levels that are not readily detected simply by visual inspection.

Does a pet's diet affect the results of the fecal occult blood test?

Yes, the pet's diet can affect the test resulting in false positive and much less frequently false negative results.

False Positive: Red meat (cooked or raw) or canned foods containing red meat such as beef, lamb and venison will often result in a false positive occult blood test. Canned foods containing chicken or fish appear to have no effect on the test. Dry food diets do not appear to affect the test.

False Negative: A diet high in Vitamin C may result in a false negative result in the fecal occult blood test. This would be an extremely unusual occurrence in dogs or cats consuming any of the standard diets.

Is there anything I can do to minimize the chances of getting a false positive result on the fecal occult blood test?

Yes. Ideally feeding a diet based on vegetable protein (such diets are now commercially available e.g. Hill's U/D) for a period of 48 hours prior to the test should virtually eliminate the chances of a false positive on the fecal occult blood test. If the pet will not readily accept this diet or if a dietary change is not advised for other health reasons, reducing or eliminating foods containing red meats or feeding an exclusively dry food diet for a period of 48 hours prior to the test should also significantly reduce the chances of a false positive result.

Effect of dietary factors on the detection of fecal occult blood in cats.
Tuffli SP, Gaschen F, Neiger R.
J Vet Diagn Invest. 2001 Mar; 13(2): 177-9

Prepared by: Dr. T. Stirtzinger
November 11, 2003