F. necrophorum (62.0%), B. melaninogenicus (43.0%), P. anaerobius (34.0%), C. sporogenes (18.0%), F. mortiferum (18.0%), B. fragilis (12.0%) and C. perfringens (12.0%) were the  most prevalent obligate anacrobic organisms isolated from bovine interdigital dermatitis. The pathogenicily of F. necrophorum in mice was related to the route of infection . Intrahepatic route was the most virulent route with mortality rate (86.7%) . Mortalities with s/c or i/p routes reached 53.3% and 73.3% respectively. The clinical signs and gross lesions were discussed in details. The in vitro sensitivity of 20 strains repreented cach of  F. necrophorum, B. melaninogenicus and P. anaerobius to 16 chemotherapeutic agents were described in details . Oxytracycline, enerofloxacine and danofloxacine were the most effective drugs against the majority of tested anaerobic microorganisms.