Evaluation of a fluorometric method for the quantitative assay of fecal hemoglobin in the dog

Feces from 27 dogs were evaluated to establish baseline fecal hemoglobin (Hb) concentrations when the dogs were fed diets containing varying amounts of Hb. Fecal Hb concentration was measured, using a quantitative fluorometric assay that was based on the conversion of nonfluorescing Hb heme to fluorescing porphyrins. Mean fecal Hb concentration was 0.31 mg/g of feces when the dogs were fed a dry diet low in Hb. This corresponded to a daily fecal blood loss of 0.043 ml/kg of body weight. The fecal Hb concentration was directly related to the dietary Hb concentration. The average recovery of orally ingested blood was 41% in 4 dogs. This fluorometric assay quantitatively detected small amounts of gastrointestinal bleeding over a wide range of fecal Hb concentrations for which feces appeared normal. Results of this study establish dietary conditions necessary for quantitative evaluation of experimental and clinical gastrointestinal bleeding.