EN
In 21 mares some indices of blood before and during pregnancy up to 11 months were being examined. During pregnancy there was found a considerable decrease of lymphocytes per cent in contrast to neutrophils whose percentage grew up during pregnancy. The content of Hb showed a highly significant drop and then an increase at months 10 and 11. At the end of pregnancy there was stated an increase of Hb and WBC as well. A significant decrease of Na, K and Ca in the serum especially at months 11 was found. After becoming pregnant the content of Mg increased and at the end of pregnancy dropped. The level of total protein was distinctly higher during pregnancy. Pregnancy did not influence the content of RBC, inorganic P and the percentage of acidophilic and basophilous granulocytes and monocytes.