Knockdown of FXIII-B results in more frequent re-bleeds but not an increase in blood loss in an in vivo model of bleeding. Tails of mice pretreated with apixaban (Apixa), siFXIIIB (siFXIII), or untreated (Unt) were transected and the subsequent bleed was observed over a period of 40 minutes. (A) Graphical representation of bleeding from the wound. Line thickness corresponds to bleeding severity, observed at 60-second intervals and qualitatively rated on a scale of 0 to 5: 0 (no line) is a cessation of bleeding, and 5 (thick line) is full unmitigated bleeding. (B) The number of clotting events, defined as a cessation of bleeding for 20 seconds or longer. (C) The total volume of blood lost relative to the individual mouse’s weight was quantified by spectrophotometry measuring hemoglobin. Each row (A) or point (B- C) represents 1 animal. Data are presented as the mean ± SEM. ns, P > .05; *P < .05; **P < .01.