Both lengthier FeCl₃ treatment and elevated FVIII increase thrombus stability. C57Bl/6 mice were infused with saline or FVIII to 285% of normal. Thrombosis was induced by 10% FeCl₃ application to the carotid artery for the indicated time (3 or 2 minutes). After stable occlusion, flow was monitored for 5 minutes to count embolic events (defined as a rapid increase in blood flow of at least 0.2 mL/min). (A-B) Representative flow tracings after 3- (A) and 2-minute (B) FeCl₃ application to control (saline-infused) mice, respectively. Gray shaded area represents time of vessel drying, FeCl₃ administration and vessel washing, during which flow could not be monitored. Brackets indicate the time from FeCl₃ placement to the time of vessel occlusion. Arrows show emboli (marked with E) in the 5 minutes after stable occlusion. (C) Quantification of embolization data. Each point represents a separate mouse. Mice that did not achieve stable occlusion were excluded. Lines show mean values. *P < .05.