Recently, we have shown that thiopyrylium has robust inactivation capabilities against a broad spectrum of pathogens in the human red blood cell (RBC) suspensions while retaining key RBC in vitro properties. The 24-h recovery and survival of canine red cells were measured upon autologus reinfusion of control and phototreated units. The 24-h recovery of control and phototreated RBCs was 75.7 ± 6.4% and 87.5 ± 8.5%, respectively. The time for 50% survival of labelled control RBCs was similar to that of phototreated group (206 ± 58 h vs. 255 ± 63 h, respectively). Results suggest that thiopyrylium phototreatment does not negatively affect canine RBC in vivo recovery.