HEMOSTATIC INDEXES IN HEALTHY FOALS FROM BIRTH TO ONE MONTH OF AGE

Hemostatic indices were determined in 45 healthy light breed foals, fr om birth to 1 month of age, and in 20 healthy adult (>2 years of age) light breed horses. Blood samples were obtained from each foal at 4 ag es: 1) <24 hours, 2) 4-7 days, 3) 10-14 days, and 4) 25-30 days. The f ollowing hemostatic indices were determined: platelet count; prothromb in and activated partial thromboplastin times; activity concentrations of protein C, antithrombin III, plasminogen, alpha-2 antiplasmin, tis sue plasminogen activator, and plasminogen activator inhibitor-1; plas ma protein C antigen and fibrinogen concentrations; and serum fibrin d egradation products concentration. Prothrombin and activated partial t hromboplastin times were significantly longer at birth than in older f oals. The plasma concentrations of the following were significantly lo wer at birth than in older foals: antithrombin III, plasminogen and ti ssue plasminogen activator activities, protein C antigen, and fibrinog en. Concentrations of the following were significantly higher at birth than in older foals: protein C and plasminogen activator inhibitor-1 activities and fibrin degradation products. These results indicate tha t hemostatic indices of neonatal foals differ significantly from those of older foals and adults. With the exceptions of antithrombin III an d tissue plasminogen activator activities, all hemostatic indices meas ured in foals at 1 month of age were equivalent to adult values.