Plasma zinc and iron concentrations as measurements for evaluating the influence of endotoxin-neutralizing agents in Escherichia coli endotoxin-induced mastitis.

The influence of bacterial lipopolysaccharides on plasma Zn and Fe concentrations and the endotoxin-neutralizing capacity of polymyxin B was studied in 3 dairy cows. Also, the feasibility of using plasma Zn and Fe concentrations as measurements for evaluating the influence of endotoxin-neutralizing agents in Escherichia coli endotoxin-induced mastitis was studied. A positive relationship was ascertained between the dose of endotoxin given intramammarily (IMM) and the effect on mean values of plasma Zn and Fe concentrations. Seemingly, IMM administration of polymyxin B-sulfate before the IMM administration of E coli endotoxin partially blocked the effects of endotoxin, as shown by decreases in plasma Zn and Fe.