Five sporadic or enzootic outbreaks of salmonellosis were reported in dairy cows on 5 farms in the Tokachi district of Hokkaido over a period from 1978 to 1980. The disease had been prevalent among male fattening dairy calves in this district. It was caused by
Salmonella typhimurium subserovar copenhagen.Clinical cases in each outbreak were associated with the Downer cow syndrome, mastitis, or infection with RS virus or Coronavirus.
In an enzootic of salmonellosis on a dairy farm, contact infection among cattle and environmental contamination with Salmonella were confirmed by cultural and serological procedures. Biovars of
S. typhimuriumisolated from cows and calves in the district were useful markers to clarify the epizootiological relationship of salmonellosis between cows and calves. All the strains of
S. typhimuriumisolated from cows and calves over the 3 years's period were resistant to one or more antimicrobial agents. An increase in the multiplicity of resistance pattern was recognized more frequently in the calf strains than in the cow strains. It may be related to the widespread use of particular drugs, including oxocilic acid, in calves. Salmonella strains with resistance to 7 drugs (AB-PC, OTC, CP, DSM, SDM, KM, and NA) were isolated from calves in this district in and after 1979.
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