EN
The content of red blood cells (RBC), white blood cells (WBC), haemoglobin (Hb), haematocrit (Ht) and differential leukocyte count were examined in 720 samples of blood taken from the external jugular vein from 90 Polish ponnies, males and females more than 1.5 year old. The parameters were examined for two years in periods corresponding to four seasons of the year. Most of the examined parameters characterized a seasonal fluctuation. The higher values were noted in summer but the lowest ones in the winter period.