EFFECTS OF MULTIPLE ENDOTOXIN INJECTIONS IN PONIES AND CALVES (PROSTAGLANDINS, HEMODYNAMICS, ESCHERICHIA COLI)
Abstract
The objectives of these two studies were, respectively, (1) to simulate the course of equine colic and to determine if flunixin meglumine provided any protective effects, and (2) to simulate the septic form of colibacillosis in calves and to determine if flunixin meglumine improved hemodynamic, histologic, and other responses. In both studies, animals were given multiple injections of E. coli endotoxin; the ponies were given endotoxin over a 26 hour period while the calves were given endotoxin over a 6 hour period. Companion survival studies were conducted in both ponies and calves. In the pony study, the untreated animals exhibited signs consistent with equine colic, but treated animals showed few effects following flunixin treatment. The protective effects of flunixin became apparent after the intravenous endotoxin injection at 24 hours by preventing serum eicosanoid elevations, pressure or cardiac output changes, and regional blood flow alterations. Electron microscopic examination of pulmonary arteries of both groups revealed that the flunixin meglumine treated group exhibited less endothelial damage than did the untreated group. In the calf study, flunixin meglumine again prevented the rise of the two eicosanoids in a dose related fashion while untreated calves demonstrated substantial increases in these two autocoids. Immediately following the first endotoxin injections, the untreated calves showed the classic signs of prostanoid release, namely, increased pulmonary arterial pressure and decreased cardiac output. There were no early hemodynamic changes in the flunixin treated group. While the treated calves displayed no early changes, by 6 hours there was little difference in hemodynamic measurements between the treated and untreated groups. In the companion survival study, a third treatment group was added consisting of flunixin meglumine and dexamethasone. There was one survivor of the 9 untreated calves, 4 survivors of the 8 flunixin treated calves, and 6 survivors of the 8 flunixin/dexamethasone treated group. It was concluded that, while flunixin meglumine does not improve all parameters in both species, it does have a beneficial effect on survival, which is the most important function of shock therapy.
Degree
Ph.D.
Subject Area
Veterinary services
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