Determination of skin concentrations of enrofloxacin in dogs with pyoderma

Objective: To compare serum and skin concentrations of enrofloxacin in dogs with pyoderma with those of clinically normal dogs and to evaluate concent rations in dogs with superficial versus deep pyoderma. Animals: 16 clinically normal dogs and 16 dogs with pyoderma. Procedure: Enrofloxacin (approx 5 mg/kg of body weight, PO) was administere d daily to all dogs. Serum samples and skin biopsy specimens were obtained on day 1 at 3 hours after drug administration and on day 3 immediately befo re and 3 hours after drug administration. Samples and specimens were assaye d by high-performance liquid chromatography. Morphometric analysis was perf ormed on skin biopsy specimens to determine correlation between inflammator y cells and peak tissue enrofloxacin concentration on day 1. Results: Morphometric analysis revealed high correlation between dermal inf lammatory cell count and drug concentration in dogs with pyoderma. Conclusions: At mean dosage of 5 mg/kg once daily, enrofloxacin tissue conc entrations were significantly greater in dogs with pyoderma at 3 hours afte r pill administration. Enrofloxacin tissue concentration on day 3 at 3 hour s after pill administration was 12.4 times the 90% minimum inhibitory conce ntraiton of enrofloxacin sor Staphylococcus intermedius. Clinical relevance: In dogs with pyoderma, therapeutic tissue concentraiton s of enrofloxacin are reached as early as 3 hours after drug administration (Am J Vet Res 1998:59,1599-1604)