Abstract
Doses of 2.0μg/kg of Escherichia coli serotype 0111: B55 endotoxin dissolved in 1, 000ml of pyrogen-free isotonic saline solution were administered over 5-minute periods via the jugular vein to 4 heifers. After initiation of endotoxin infusion, the heifers were monitored until 240 minutes had passed. After decreasing progressively, at t=30min, the relative plasma volume had dropped to 67.4±6.0% and partial oxygen pressure to 56.4±2.4mmHg. Thereafter, they remained constantly at low levels. The arterial-alveolar O2 gradient increased progressively to 44.6±3.2mmHg by t=30min. These results suggest that this model meets experimental requirements for examination of the bovine respiratory-disease complex.
