WBCT in tolerized hemophilia B dogs. The average WBCT values obtained quarterly from the 5 tolerized dogs are listed. Four dogs survived for 3.5 years, and the fifth died during year 2. At baseline (first value shown) and after 3.5 years of subcutaneous prophylaxis, the average value was markedly prolonged. The ^* denotes a sample drawn during a rhFIX-free washout period. The horizontal lines mark the WBCT range for healthy dogs (8-12 minutes) and for untreated hemophilia B dogs (> 60 minutes). Maintenance with subcutaneous rhFIX was started at day 112 as described in Table 1 and adjusted to 82.6 IU/kg twice weekly at day 178. This treatment markedly shortened the WBCT. All samples were drawn just prior to the next dose. Error bars indicate SD.