Mogens Agerbo Krogh

Abomasal lesions in dairy cattle are highly prevalent, but diagnosis of the non-penetrating lesions is a challenge. We performed one experiment to estimate the amount of blood detectable in feces using two different tests, one experiment to determine if hemoglobin is degraded in the rumen to find possible false-positive tests due to blood from extra gastrointestinal sources and subsequently an observational study to estimate the diagnostic properties of the test with the observed lower detection limit. The observational study included primarily dairy cattle at slaughter, where we could observe the actual lesions postmortem. The detection limits of the tests marketed as Hemo-Fec® and Hemoccult II® SENSA® were 1–2 mL blood/kg feces and 2–4.5 mL blood/kg feces, respectively. Hemoglobin was not degraded in ruminal fluid and could possibly bypass the rumen and be detected in feces. In the observational study, the Hemo-Fec® test had no diagnostic value in dairy cattle with superficial erosions, with scarring, and with <4 acute or chronic lesions. The test had diagnostic potential in cattle with ≥4 acute or chronic lesions, where the proportion of true positives exceeded the proportion of false-positive results. However, many false-positive reactions make the use of the test a challenge.