AMOXICILLIN AS AN ALTERNATIVE TO DIHYDROSTREPTOMYCIN SULFATE FOR TREATING CATTLE INFECTED WITH LEPTOSPIRA-BORGPETERSENII SEROVAR HARDJO

Objective To assess the effect of amoxycillin treatment on urinary exc retion of leptospires from cattle infected with Leptospira borgpeterse nii serovar hardjo. Design A chemotherapy trial with controls. Procedu re Fourteen heifers serologically negative to L hardjo were inoculated with L hardjo via the conjunctival route and assessed for evidence of infection by serological, fluorescent antibody and microbiological te sts. Two injections (48 h apart) of amoxycillin at a dose of 15 mg/kg were administered intramuscularly to seven heifers 6.5 weeks after inf ection; the remaining heifers acted as untreated controls. Later, thes e seven control group heifers were treated with a single dose of amoxy cillin (15 mg/kg). Samples of urine were collected before and after am oxycillin treatments; kidneys were collected at slaughter, and examine d by fluorescent antibody test and microbiological culture. Results Le ptospires were isolated from the urine of 11 of 14 heifers inoculated with L hardjo. After treatment of six of these with two injections of amoxycillin, leptospires were not isolated. Of the controls, four of t he five initially leptospiruric heifers continued to shed leptospires; after a single injection of amoxycillin, no leptospires were detected in the kidneys of these four.Conclusion Amoxycillin may be an accepta ble alternative to dihydrostreptomycin sulphate for the treatment of c attle infected with L hardjo.