Sensitivity of fecal occult blood testing in the cat

Objectives The impact of dietary factors on fecal occult blood (FOB) testing has been previously evaluated in cats, but the analytical sensitivity of this point-of-care test remains unexamined. The primary goal of this study was to assess the analytical sensitivity of the FOB test in cats. Methods Five cats were used in a repeated measures study. Following oral administration of blood, feces were collected and tested every 12 h for FOB and melena. All cats were fed an animal protein-free diet starting the week before entry into the study. Blood was administered on a milligram of hemoglobin per kilogram of body weight basis, and dosed at 1.5, 3, 15, 30 and 45 mg/kg hemoglobin in series with a wash-out period between each trial. Results FOB was detected in one cat at 1.5 mg/kg hemoglobin, three cats at 3 mg/kg hemoglobin and in all five cats at 15, 30 and 45 mg/kg hemoglobin. Melena was noted in one cat at 30 mg/kg and four cats at 45 mg/kg, but not at lower doses. Conclusions and relevance Administration of 15 mg/kg hemoglobin (equivalent to about 1.5 ml blood) was sufficient for positive results in all cats. However, detection occurred with as little as 1.5 mg/kg hemoglobin. Thus, FOB has good analytical sensitivity in cats under appropriate clinical situations.