Culturable Microbial Population From the Upper Respiratory Tract of 1,010 Clinically Healthy Horses in Southern Brazil

•The upper respiratory tract of healthy horses presented a diverse microbial population.•Gram-positive and negative were found in 82.91% and 40.29% of horses, respectively.•The most occurrent profile was Staphylococcus sp. + Gram-negative bacilli.•Pathogenic bacteria were isolated colonizing the nasal cavities of clinically healthy horses with the commensal.