Antibiotic levels in bovine lacrimal fluid after single application of ointments containing procaine benzyl penicillin plus dihydrostreptomycin; and benzathine cloxacillin.

The efficacy of an experimental slow-release formulation, containing procaine benzyl penicillin and dihydrostreptomycin, was investigated in a cross-over study with a cloxacillin eye ointment in 12 cows with clinically normal eyes. After a single topical application the therapeutic concentrations of penicillin were sustained for 48 to 92 hours and of cloxacillin for 32 to 48 hours. These long-acting ointments will simplify the successful treatment of painful eye disorders such as keratoconjunctivitis. A practical and non-irritant method for sampling tears is described.