EFFECTS OF PENTOXIFYLLINE AND POLYMYXIN-B ON THE ACUTE-PHASE-RESPONSETO ESCHERICHIA-COLI ENDOTOXIN IN DWARF GOATS

The purpose of this study was to assess whether polymyxin B together w ith pentoxifylline, had beneficial effects on the acute-phase-response to E. coli endotoxin in the dwarf goat (n = 6). Polymyxin B partly ne utralizes E. coli endotoxin by forming inactive polymyxin B-lipopolysa ccharide (LPS) complexes; pentoxifylline has been reported to suppress the LPS-induced production of tumour necrosis factor (TNF-alpha). E. coli LPS (0.0067 mu g/kg/min over 30 min) induced fever, tachycardia, inhibition of rumen motility, a decline in WBC, lymphopenia, and decre ases in plasma zinc and iron concentrations. Most of the haematologica l, blood biochemical and clinical effects of E. coli LPS were signific antly reduced by polymyxin B pretreatment (0.1 mg/kg/min over 30 min, i.v.). Pentoxifylline (0.3 mg/kg/min over 30 min, i.v.) did not reduce the clinical and blood biochemical effects of E. coli LPS, however, i t modulated the number of circulating neutrophils. No synergistic effe cts were observed after i.v. infusion of polymyxin B with pentoxifylli ne. The lack of synergy may be due to the production and release of pr o-inflammatory cytokines other than TNF-alpha.