The current study aimed to characterize the bacterial causes of respiratory diseases in clinical, subclinical and carrier horses of different ages .159 nasal swabs were collected from the internal nares of horses suffered from respiratory manifestation which classified into three groups; foreign breed (29), native breed (73), and Arabian breed (57). The main isolate was of
S. equi subspp. Equi recovered from foreign breed in an incidence of 15.7%, and from native breed in an incidence of 30.7%, while the incidence of other detected bacteria of the foreign breed was E. coli, and k. pneumoniae in an incidence of 66.6% and 16.6%, respectively. The native breed and Arabian horse breeds recorded only E. coli in an incidence of 100% for each. It could be concluded that the respiratory manifestations of bacterial caused by S. equi is commonly identified mixed with E. coli and k. pneumoniae.