Intramammary antibiotics in dairy goats: withdrawal periods of three intramammary antibiotics compared to recommended withdrawal periods for cows.

Intramammary antibiotics are registered and tested for use in dairy cattle. This study investigated withdrawal periods of three intramammary antibiotics (Curaclox LC [Norbrook Pharmacia AH]), Spectrazol Milking Cow (Schering-Plough Animal Health) and Rilexine 200 LC (Logos Agvet [Virbac]) in dairy goats and compared them to withdrawal periods recommended for use in cattle. Three trials were carried out in two different herds. The withdrawal periods for Curaclox LC in eight relatively low producing Saanen goats were 74.3 h (+/- 19.21) measured by Thermo-Resistant Inhibitory Substances (TRIS), 90.0 h (+/- 16.97) measured by colour dye, 99.4 h (+/- 9.07) for cloxacillin measured by Parallux Beta Lactam Assay test (IDEXX distributors), and 92.6 h (+/- 11.41) for ampicillin measured by Parallux. The withdrawal period for Curaclox LC recommended for use in cattle (72 h) was significantly shorter than the withdrawal periods as measured by colour dye (P < 0.001), Parallux testing for cloxacillin (P < 0.001) and ampicillin (P = 0.003). There was a significant difference in withdrawal periods as measured by TRIS (P = 0.009) and colour dye (P = 0.036). The mean withdrawal periods measured on 12 relatively high producing Saanen and Saanen-Toggenburg crossbreed dairy goats measured by TRIS, colour dye and Parallux for ampicillin and cloxacillin were, however, shorter at 42.0 h (+/- 7.077), 64.5 h (+/- 60.26), 77.3 h (+/- 13.56) and 70.7 h (+/- 12.65), respectively. These withdrawal periods for Curaclox LC were significantly longer than the withdrawal periods recommended for cattle as measured by TRIS (P < 0.001) and colour dye (P < 0.001). The combined withdrawal periods for Curaclox LC in the two trials as measured by TRIS, colour dye, Parallux testing for Cloxacillin and Ampicillin were 58.64h (+/- 24.31), 75.8 h (+/- 17.70), 87.0 h (+/- 16.10) and 80.3 h (+/- 16.23), respectively. The withdrawal period, when data of the two trials were combined, measured by TRIS (P < 0.001) was significantly longer than the withdrawal period recommended for use in cattle. The mean withdrawal period as measured by TRIS for Spectrazol Milking Cow for seven relatively low producing Saanen dairy goats was 95.3 h (+/- 17.23). This was significantly (P < 0.001) longer than the withdrawal period recommended for use in cattle (60 h) for Spectrazol Milking Cow. The mean withdrawal period as measured by TRIS for Rilexine 200 LC for 20 relatively high producing Saanen and Saanen-Toggenburg crossbreed dairy goats was 36.9 h (+/- 9.943) and was significantly (P < 0.001) shorter than the withdrawal period as recommended for use in cattle (96 h). There were also significant differences in all the one-sample t-tests between withdrawal periods for goats and recommended withdrawal periods for cattle without the 24 h safety margin.