EN
Parameters of blood clotting were elaborated by examining 84 horses of various breeds, males and females ageing from 5 months to 25 years in four seasons of a year. The animals were situated in a few breeding centers. The following parameters were examined in blood taken from the external jugular vein: coagulation time of full blood, kaolin-kephaline time, protrombine and trombine time, content of fibrinogen and in 15 Polish ponnies additionally the level of antitrombine III. The results were statistically evalueted in the t-Student test. It was found that a mean coagulation time was 12 min., kaolin-kephaline time 120 sec., protrombine time 14 sec., trombine time 27 sec., level of fibrinogen 3.7 g/l, concentration of antitrombine III 20.4 iu/ml. These values were smaller in English fullblood horses. Moreover in females the trombine time (29.5 sec.) and the content of fibrinogen (3.93 g/l) is higher than in males (25.0 sec. and 3.41 g/l, respectively). The high content of plasma antitrombine III points that a slow course of blood coagulation is a species related phenomenon.