The aim of this study was to determine the influence of anticoagulants on dog platelet activation. The investigation was carried out by evaluating the expression CD61 and fosfatydyloserin as a marker of activation. In vitro data platelet activation was obtained by PMA and for the stabilization of the cell membrane procaine was used. Thrombopoesis was evaluated by reticulated platelets. It was shown that the platelets number was dependant on anticoagulants, and was greater in EDTA-3K blood, and the expression of CD61 was the largest on normal platelets in EDTA-3K platelet-rich plasma (PRP). The number of activated platelets was the highest among aggregates and the highest percentage of CD61+AnV+ did not depend on the use of anticoagulants. The percentage of platelets and microparticles with the expression of those antigens influenced by procaine, microparticles and aggregates influenced by PMA was higher in citrate PRP than EDTA-3K PRP. It was observed that anticoagulants did not have any influence on the percentage of reticulated platelets and the highest number of them can be found in among aggregates.