Randomized clinical trial to evaluate the efficacy of a 5-day ceftiofur hydrochloride intramammary treatment on nonsevere gram-negative clinical mastitis.

The objective of this study was to evaluate the efficacy of intramammary treatment with ceftiofur hydrochloride of nonsevere, clinical coliform mastitis. One hundred four cases on 5 farms met the enrollment criteria for the study. Escherichia coli was the most common coliform species identified in milk samples from cows with mild to moderate clinical mastitis, followed by Klebsiella spp. and Enterobacter spp. At enrollment, a milk sample from the affected quarter was taken and used for on-farm culture or submitted to the laboratory. For cows in the treatment group, treatment was initiated with ceftiofur hydrochloride via intramammary infusion at 24-h intervals for 5 d according to label standards. Cows in the control group did not receive treatment. Culture results were available on the day after enrollment and only cows with coliform mastitis continued in the treatment and untreated control groups. Bacteriological cure was defined based on 2 posttreatment milk samples. Molecular typing was used for final definition of bacteriological cure. Treatment of nonsevere clinical gram-negative mastitis with ceftiofur hydrochloride resulted in a significant increase in bacteriological cure compared with nontreated controls in animals infected with E. coli or Klebsiella spp. Treated animals clinically improved significantly more compared with control cows. No significant differences were observed between treated and control animals in milk production or linear score before or after clinical mastitis. Treated animals left the study less frequently compared with control animals.

Effect of an insecticide controlled-release bolus on a milk antibiotic residue test.

Following the use of diflubenzuron controlled-release insecticide boluses in a dairy herd, there was a concern that post-calving cows were testing positive on a milk antibiotic residue test for more milkings than they had prior to the use of diflubenzuron. A field trial was conducted to examine for possible effects of diflubenzuron milk residues on the milk antibiotic residue test, Delvotest-P. Data of 24 cows in the treatment group and 29 cows in the control group were analyzed. There was no significant difference in the number of milkings after calving in which the milk tested positive on the milk antibiotic residue test between the treatment (2.75 +/- .94) and control (2.97 +/- 1.05) groups when cows in all lactations were analyzed or when analyzed by lactation (1, 2, and greater than or equal to 3). It was concluded that the use of diflubenzuron boluses had no effect on the milk antibiotic residue test.