Abortion and serological reaction of ewes after conjunctival instillation of Salmonella enterica subsp enterica ser abortusovis.

The aim of the experiment was to evaluate in pregnant ewes the clinical, bacteriological and serological effects of conjunctival instillation of S abortusovis. An individual dose of 1 x 10(10) viable S abortusovis were administered to 20 ewes 92 d after mating. Among 18 pregnant ewes, 8 aborted 110 +/- 13 d after mating, 4 had stillborn lambs and 6 a clinically normal lambing (114 +/- 1.3 d). S abortusovis was isolated from placentas, swabs and foetuses of the 12 lambings. Evolution of "H" agglutination titers measured by means of a microtechnique using a coloured antigen was found to be independent of the clinical results. Instillation by conjunctival route could constitute an experimental model closer to a natural mode of infection than the subcutaneous route.