Fecal occult blood tests in cattle

Three methods for fecal occult blood detection were evaluated in mature cows. Bovine blood (heparinized) was infused directly into the abomasum of mature nonlactating rumen-fistulated cows. After administration of the blood, feces from the cows were periodically collected, tested, stored, and retested. Sensitivity for two of the three methods was optimal at 2 days of storage, regardless of temperature at storage. A dilute alcoholic solution of guaiac was the most sensitive and reproducible method. In vitro tests demonstrated that guaiac solution could detect a quantity of blood comparable with a daily blood loss of 69 to 75 ml. In addition, the minimal transit time of blood from abomasum to rectum was measured and ranged from 7 to 19 hours.