The effect of vaccination on the course of an experimental Salmonella typhimurium infection in racing pigeons

Two killed adjuvanted vaccines were evaluated for their efficacy against sa lmonellosis in pigeons. Both vaccines contained whole-cell formaldehyde-ina ctivated Salmonella typhimurium var. Copenhagen bacteria. Two groups of 10 pigeons were inoculated twice with a 3-week interval with one of the vaccin es. Ten weeks after the second vaccination, all vaccinated pigeons as well as 10 non-vaccinated birds were challenged by crop inoculation of 10(9) col ony-forming units of a Salmonella serotype Typhimurium var. Copenhagen stra in. Ten pigeons that were not vaccinated or challenged served as negative c ontrols. As determined by clinical examination, plasma chemistry and necrop sy, neither vaccine induced protection against challenge. The only signific ant effects observed were a reduction in the level of faecal shedding and a less severe polydipsia in the pigeons treated with one of the two vaccines . Results of this study indicate that vaccination against salmonellosis in pigeons with killed vaccines may not be very useful. However, the ability o f certain vaccines to reduce shedding may contribute to the control of salm onellosis in infected pigeon lofts.