EFFECT OF PHENYLBUTAZONE AND REPEATED ENDOTOXIN ADMINISTRATION ON HEMOSTASIS IN NEONATAL CALVES

Twenty newborn Holstein calves were allotted at random to 4 groups: gr oup A received 0.9% sterile saline solution; group B received phenylbu tazone (5 mg/kg of body weight, IV) and 0.9% sterile saline solution; group C received progressively increasing; doses of endotoxin (0.1 to 15 mug/kg); and group D received phenylbutazone and endotoxin similarl y as did calves of groups B and C, respectively. Phenylbutazone was gi ven once daily and saline solution or endotoxin were given every 8 hou rs for 5 days. Clinical variables-PCV, plasma total protein and fibrin ogen concentrations, platelet count, prothrombin time, activated parti al thromboplastin time, and fibrin degradation products concentration were measured at 24-hour intervals. Necropsy was performed on each cal f Phenylbutazone suppressed the clinical response to endotoxin challen ge until large doses (7.5 to 15 mug/kg) were administered. Calves of g roups C and D remained stable until they abruptly developed severe dys pnea necessitating euthanasia. Thrombocytopenia and leukopenia develop ed after the initial endotoxin dose. Prothrombin time was prolonged an d PCV suddenly decreased at 96 hours. Necropsy revealed consistent les ions in the vascular endothelium and lungs. Phenylbutazone administrat ion did not enhance or ameliorate endotoxin-induced hemostatic alterat ions or pathologic lesions.