Forensic luminol reaction for detecting fecal occult blood in experimental mice

Fecal occult blood (FOB) is a sign of gastrointestinal diseases, such as intestinal ulcers and colorectal cancer. In experimental animal studies, there is no standard method to detect FOB. Here, we present a simple protocol to detect FOB in mice, using the Luminol Reaction Experiment Kit(®) that was originally designed to detect bloodstains at a crime scene in criminal forensics. To obtain positive control bloody feces, we used an indomethacin-induced intestinal ulcer model in mice. By mixing small pieces of feces with a luminol solution, the fecal solution emitted visible blue–white chemiluminescence in dark field when feces contained hemoglobin. We also established a method for semi-quantification of hemoglobin content in the fecal solution, using a luminometer. This method is simple, quick, economical and semi-quantitative, allowing researchers to detect FOB in experimental mice.