Comparison of the distribution of tobramycin and gentamicin in body fluids of dogs.

Tobramycin serum, thoracic lymph, renal lymph, and urine concentrations were measured in mongrel dogs after intravenously administered 5, 10, and 20 mg/kg doses. These were compared with intravenous gentamicin delivered at 5 and 20 mg/kg. Both drugs achieved similar concentrations in serum and thoracic lymph. At 20 mg/kg, tobramycin showed consistently higher renal lymph and urine concentrations than gentamicin. At 5 mg of tobramycin per kg, renal lymph and urine concentrations were higher than with gentamicin only within the 1st h after administration. Thereafter the difference was no longer significant. These data suggest that on the basis of distribution in the body fluids of dogs, tobramycin is a reasonable alternative to gentamicin.