Abstract

Salmonellosis occurs in many animal species including sheep, and may cause pathology of the gut and possible abortion. If attenuated strains were to be used for future control, their establishment in the host and shedding pattern needs to be determined. Fifty-one pregnant ewes were obtained from the Lincoln University Research Farm and assigned randomly to five treatment groups. At approximately 1 month before lambing, the groups were given attenuated S. typhimurium (cya-, crp-) by different routes and doses as follows: 1010 colony-forming units (cfu) intranasally (i.n.), 109 cfu i.n., 1010 cfu subcutaneously (s.c.), 109 cfu s.c., and control (saline i.n. and s.c.). Selected animals were slaughtered at days 4 and 14 post infection for bacteriological culture from the mesenteric and retropharyngeal lymph nodes, intestinal contents and lamb stomach contents. The experimental organisms were isolated using selective cultures and identified by latex agglutination test and fermentation reactions. Following infection there were no changes in rectal temperature or significant clinical signs except two cases of abortion in the 1010 cfu s.c. group. The number of animals shedding organisms in their faeces decreased with time from 12 ewes at day 1 to one ewe at day 4 and day 7. Most of them were from the 1010 i.n. group. Subcutaneous injection of 1010 cfu induced abortion in two of 11 ewes, as organisms were detected in their faeces and the aborted lambs. However, no organisms were detected in faeces, intestinal contents or the lamb stomach contents of the ewes that were killed at days 4 or 14. In the two ewes that had received 1010 cfu i.n. and were killed at day 4, organisms were detected in the mesenteric and retropharyngeal lymph nodes. In summary, the administration of the attenuated S. typhimurium (cya-, crp-) at 1010 cfu caused asymptomatic short-term faecal shedding and abortion when given i.n. and s.c., respectively.

AM, Khalil, RG McFarlane, NA Shand, SE Leslie, and NH Christensen

Proceedings of the New Zealand Society of Animal Production, Volume 61, Christchurch, 74-77, 2001