CLINICAL EFFICACY OF AMPICILLIN, PIVAMPICILLIN AND PROCAINE PENICILLIN-G IN A SOFT-TISSUE INFECTION MODEL IN PONIES

Tissue chambers, implanted subcutaneously in ponies, were inoculated w ith Streptococcus zooepidemicus. The animals received either no antibi otics or one of the following treatments: pivampicillin per os (19.9 m g/kg, equivalent to 15 mg/kg ampicillin, every 12 h) for 7 or 21 days (7 and 5 ponies, respectively), procaine penicillin G intramuscularly (12 mg/kg = 12,000 IU/kg, every 24 h) for 7 days (7 ponies), or ampici llin sodium intravenously (equivalent to 15 mg/kg ampicillin, every 8 h) for 1 day (5 ponies), Only intravenous administration was started b efore infection (prophylactically), the other treatments were started 20 h after infection (curatively). A total of 7 ponies received no ant ibiotics, In untreated controls, the infection led to abscessation of the tissue chamber in 4 to 10 days. Curative treatment with either piv ampicillin or procaine penicillin G for 7 days resulted in a reduction of viable bacteria in the tissue chamber but did not eliminate the in fection, resulting in abscessation in 5 to 14 days, However, administr ation of pivampicillin for 21 days eliminated the streptococci in five out of five ponies and prophylactic administration of ampicillin was successful in three out of five ponies.