Experimental Salmonella arizonae infection of sheep.

Abstract

At approximately 12 weeks gestation, eight ewes were dosed orally with 3·9 × 109, Salmonella arizonae (61:k:1, 5, 7). No abnormal clinical signs were observed and the challenge organism was recovered from the faeces of all the ewes for up to two weeks. At approximately 16 weeks gestation, the original eight ewes and seven other ewes were dosed with 7·5 × 109, S. arizonae. Abnormal clinical signs were not observed and all the ewes, with the exception of a barren ewe, lambed within five days of the expected date. Faecal excretion of S. arizonae was sporadic, the last isolation occurring 28 weeks after the second challenge. S. arizonae was not isolated from any of the lambs at birth and during the two months suckling period it was isolated from only one of the lambs. Five ewes were served again and S. arizonae was recovered periodically during the nine weeks prior to parturition. At post-mortem examination of the ewes, S. arizonae was isolated from only one of them. In a second experiment, 10 lambs were infected with S. arizonae doses ranging from 2·5 × 104 to 4·3 × 108. One lamb which had low serum immunoglobulins died after challenge with 106 organisms. The other lambs excreted S. arizonae in their faeces for up to six days and it was recovered from the large intestine of one at post-mortem examination.