[The pathogenesis of coliform mastitis (author's transl)].

The present paper is a report on a comparative study of the effects of intravenous or intramammary injection of various doses of E. coli endotoxin in normal and endotoxin-tolerant animals on a number of clinical and clinicochemical parameters. The absence of marked effects on rumen motility following intramammary administration of endotoxins raised serious doubts as to the validity of the common theory of absorption of endotoxins from the udder in these animals. Experimental animals were made tolerant by daily intravenous injections of E. coli endotoxins. Animals tolerant for a single intravenous injection also were tolerant for intravenous infusion of E. coli endotoxins. Intramammary administration of one fifth of the dose of endotoxins for which the animals had been made tolerant, produced a maximum effect on the body temperature and plasma zinc concentrations of cows. In view of these findings, it can be postulated that the systemic symptoms in E. coli endotoxin induced mastitis are not due to the absorption of endotoxins from the udder.