Endotoxin-induced fever and associated haematological and blood biochemical changes in the goat: the effect of repeated administration and the influence of flurbiprofen

Abstract

Flurbiprofen, a potent non-steroidal anti-inflammatory and antipyretic agent, was given as an intravenous infusion (2 mg/kg) followed by a bolus injection of 1 mg/kg six hours later. After drug administration body temperature and rumen contractions were slightly depressed, whereas urea values gradually increased; serum sorbitol dehydrogenase (SDH) activity, plasma iron concentration and the number of circulating lymphocytes were significantly lower. Intravenous injection of endotoxin from Escherichia coli O111B4 (0.1 microgram/kg) caused shivering, fever, inhibition of rumen contractions, changes in heart rate, lymphopenia, neutropenia followed by neutrophylic leucocytosis, changes in urea values, hypoferraemia, hypozincaemia and a decline in serum alkaline phosphatase (ALP) activity, whereas gamma-glutamyltranspeptidase, glutamic oxalacetic transaminase, lactic dehydrogenase and SDH values were not significantly altered. Pretreatment with flurbiprofen completely abolished the febrile reactions to endotoxin. The endotoxin-induced inhibition of rumen contractions was only delayed. The drug blocked the initial tachycardia to endotoxin but did not prevent the secondary biphasic increase in heart rate. Flurbiprofen failed to modify the endotoxin-induced decrease in both plasma zinc and serum ALP activity whereas the decline in plasma iron concentration was delayed. After drug pretreatment the changes in circulating white blood cells were more pronounced. These data demonstrate that most of the haematological, blood biochemical and clinical effects of endotoxin cannot be blocked by flurbiprofen, and that these effects are not due to the increase in body temperature alone. Tolerance induced by repetitive daily intravenous administration of endotoxin resulted in an almost complete abolition of all the effects. However, the plasma iron values from tolerant goats were significantly lower than those from non-tolerant animals, which demonstrates that the development of a refractory state can result in modification of this biochemical parameter.