Treatment of primary and secondary infections of the airways, such as rhinitis caused by Pasteurella spp. and Streptococcus spp., and bronchopneumonia caused by Pasteurella spp., Escherichia coli and Gram-positive cocci. Treatment of primary infections of the urogenital tract, such as pyelonephritis and infections of the lower urinary tract caused by Escherichia coli, Proteus spp. and Gram-positive cocci, endometritis caused by Escherichia coli, Streptococcus canis and Proteus spp., and vaginitis as a result of mixed infections. Treatment of mastitis caused by Gram-positive cocci and Escherichia coli. Treatment of local skin infections caused by Streptococcus spp.