Abstract: In order to identify the cause of joint abscess and diarrhea of dairy cows in Gansu province and choose sensitive drugs for treatment,clinical samples were isolated and identified by BVDV and BRV detection, bacteria isolation and culture, mouse pathogenicity, antibiotic sensitivity tests and content detection of Ca and P in the sera which were collected from diary cows suffering from joint abscess and diarrhea. The results showed that mix infection of pathogenic Proteus mirabilis and E.coli causing joint abscess and diarrhea of dairy cows. The two isolates were medium sensitive to florfenicol,resistant to penicillin,amoxicillin, gentamicin, kanamycin neomycin,tetracycline, norfloxacin and cotrimoxazole. This disease was controlled by the treatment of florfenicol and enhancing feeding management.

Key words: Proteus mirabilis; E.coli; joint abscess; diarrhea; dairy cows