Abstract

In this study 60 local calves breed (30 animals of with otitis externa and 30 without otitis externa) of both sexes, three weeks to six months old were examined clinically and bacteriologically for isolaltion and identification of the bacterial agents from external otic canal. The main clinical signs observed in animals with otitis externa included auricular discharge (unilateral in 23 and bilateral in 7 calves), cough, nasal discharge, anorexia, and emaciation. Results revealed isolation of (9) bacterial species from external otic canal in both calves with otitis externa and without otitis externa. The predominant species found in calves with otitis externa were Pasteurella multocida, Mannheimia hemolytica and Staphylococcus aureus, while in the calves without otitis externa were Escherichia coli, Klebsiella pneumonia, and Staphylococcus epidermis. Results also indicated that the most bacterial isolated from calves with otitis externa were resistance to the bactericidal effect of the calf normal serum and produced hydroxymate siderophore in comparison with bacterial isolated from calves without otitis externa.