Appraisal of the suitability of a disease model of acute salmonellosis in calves for chemotherapeutic studies.

When young calves were dosed orally with 10(10) organisms of a culture of Salmonella dublin, typical symptoms of acute salmonellosis followed with a death rate of 86 per cent. Peak mortality occurred six days after infection. As a result of a statistical appraisal of the consistency of mortality in groups of untreated calves a model is proposed for the therapeutic evaluation of antibacterial compounds, which compares the number of survivors in groups of seven or eight calves with a minimum of four needed for significant indication of efficacy. Bacteriological and pathological investigations showed that the experimental disease was initially an acute systemic infection followed by severe enteritis. Measurements of plasma concentrations of enzymes and other constituents did not achieve the desired objective of establishing a method of quantitative evaluation of the clinical status of individual animals, although some changes occurred which were consistent with the pathology of the disease and suggested possible mechanisms by which jaundice occurred.