Therapeutically relevant concentrations of Baytril® in the milk are maintained for more than 24 hours after application of 2.5 mg enrofloxacin/kg bw. The mean values for i.v., i.m., and s.c. administration can be seen in the relevant graphs.
The kinetics in milk are influenced by the route of administration. The highest peak concentrations in milk are achieved after intravenous application.

Field trial in Northern Italy to evaluate the efficacy of two different therapies against acute clinical mastitis in dairy cows

Evaluation of four fluoroquinolone treatment regimens for acute bovine mastitis

A trial on the treatment of induced  E.coli  mastitis with Baytril® was conducted (Hoeben BD et al., J  Dairy Res. 2000 Nov; 67(4): 485–502). Twelve cows were infected with 10 4 cfu E.coli P4:032 into both left quarters. Six cows received an intravenous injection of 5 mg enrofloxacin/kg at ten hours after infection and a second Baytril® treatment administered subcutaneously at 30 hours after infection. The other six cows were controls that received no treatment.

The clinical scores for induration of mammary gland parenchyma and swelling of the mammary gland were compared, as were milk yield and milk composition with regard to lactose.

In addition to the reduction of bacteria in the infected quarters, Baytril® reduced the severity of the disease, the decline in milk production, and the changes in milk composition.

The efficacy of Baytril® in mycoplasma mastitis was assessed in a study by Wendt et al. in 2001 (Wendt K et al., XXII World Buiatric Congress, Hannover,  Aug 2002). 45 cows with confirmed mastitis caused by M. californicum were included in the study. 22 cows (7 dry, 15 lactating) were treated with Baytril® (5 mg enrofloxacin/kg on three consecutive days); 23 cows were left untreated as controls.
There was a remarkable improvement in somatic cell count in the milk of treated lactating cows, which persisted as much as one month after treatment compared to the controls.

14 of the lactating cows were bacteriologically fully cured and 11 were cured clinically as well as functionally (one cow was slaughtered before the end of trial) and five out of seven dry cows (two slaughtered before the end of trial) were mycoplasma negative.
In vitro data and clinical findings show that Baytril® is successful in treating mastitis caused by susceptible pathogens.