Preliminary study of tissue concentrations of penicillin after local administration into the guttural pouches in four healthy horses.

BACKGROUND: Treatment of subclinical carriers of Streptococcus equi subsp. equi with a gelatine-penicillin formulation deposited in the guttural pouch has been empirically proposed, but data on local tissue penicillin concentrations after treatment are lacking.

METHODS: We analysed tissue levels of penicillin after administration into the guttural pouches of four healthy horses. Two horses received local treatment with gelatine-penicillin and two horses received local treatment with an intramammary formulation of penicillin. Tissues were harvested for analysis either 12 or 24 h later.

CONCLUSION: Results indicate that local treatment may be effective, but more research on optimal drug formulations in a larger sample size is warranted.