Pathogenetic factors in experimental bovine oesophagostomosis. V Intestinal bleeding as cause of anemia.

Abstract Fecal blood loss from 13 calves experimentally infected with Oesophagostomum radiatum was measured using 51 Cr-labeled erythrocytes. Bleeding into the parasitized colon commenced 3 weeks after infection, at the time of the fourth larval ecdysis, and persisted for at least 9 weeks. Maximum erythrocyte losses (mean 39 ± 14 ml packed erythrocytes/day) occurred during the seventh week after infection and were associated with a mean worm burden of 2500 adult parasites. The mean value of the maximum daily erythrocyte losses expressed as a percentage of the total red cell volumes was 3.5 ± 0.9%. A mean total red cell loss equivalent to 8.5 liters of jugular whole blood was estimated to have occurred between 3 and 12 weeks after infection. It was concluded that intestinal hemorrhage is the prime cause of the anemia associated with Oesophagostomosis.