Healthy horses were randomly allocated into 4 equal groups that received placebo injections ( control ) or IV administration of enrofloxacin ( 5 mg/kg [ 2.3 mg/lb ] , 15 mg/kg [ 6.8 mg/lb ] , or 25 mg/kg [ 11.4 mg/lb ] of body weight , q 24 h ) for 21 days .
