Study On The Dynamic Variation In Ducklings By Artificially Infected With Pasteurella Multocida Anatis

By oral infection and instillated intranasally infection with virulent Pasteurellamultocida anatis in ducklings, took heart, lever, lung, kidney and thymus at 6, 12,18 and 24 hours after infection to count live bacteria And took heart, lever, lung,kidney, spleen, thymus, bursa, stomachus glandularis and duodenum to pathologic.Main results were as follows:The LD₅₀ of instillated intranasally infection is 1×10^-4.5/0.2mL,and oral infection is1×10^-2.375/0.2mL.It indicated the virulence of instillated intranasally infection was higherthan oral infection's.At 12 hours after infection, detected pathogenic bacteria in thymus, liver, heart, lung.At 18 hours after oral infection detected pathogenic bacteria in kidney, and at 24 hoursafter instillated intranasally infection. At 12 hours after oral infection, thymus was5.33×10³, the highest bacteria number. Liver, lung, heart and kidney got lower one by one.At 12 hours after instillated intranasally infection, lung was 5.00×10³, the highest bacterianumber. Thymus, Liver, heart and kidney got lower one by one. At 24 hours, the thymus'snumber was the highest in both oral infection and instillated intranasally infection. Theresults indicated the thymus and lung were the best organs to detective Pasteurellamultocida anatis and isolated pathogenic bacteria, then was liver. From 6-12h was thelogarithms proliferation period of Pasteurella multocida anatis. The bacteria number in allorgans were not significant from 12-24h, and it indicated the immune response inducklings depressed the growth of Pasteurella multocida anatis.At 6 hours, organs exhibited the most earliest pathological changes in digestive tractinfection, and respiratory tract infection was earlier than 6 hours. All organs were observedcongestion at 6 hours after oral infection. From 6-12h, all rogans showed swelling anddegeneration. From 12-18h, showed condensation and fragmentation of nucleus. From 18-24h, the pathological changes got worse, lymphocyte infiltration, and the proliferationof endothelium. Instillated intranasally infection was the same as oral infection, but thepathological changes was in advance. Pasteurella multocida anatis also caused immuneorgan injury, especially in thymus and spleen.