Microscopic organ involvement. After staining with hematoxylin and eosin, piglet kidney histology specimens were evaluated microscopically in a blinded fashion by a single pathologist and assigned values on a scale from 0–5 (0: no involvement; 1: minimal; 2: mild; 3: moderate; 4: moderately severe; and 5: severe) for two different categories: congestion and hemorrhage. Thrombosis was rated by presence (+1) or absence (0). AT: antithrombin III (50 μg/kg bolus, and 25 μg/kg continuous intravenous infusion); R-TPA: recombinant tissue plasminogen activator (0.025 mg/kg/hr). Data are expressed as Mean ± SD (standard deviation). Group A: n = 4; Group B: n = 5; Group C: n = 4; Group D: n = 5. * P < 0.05 compared with supportive care alone.