Canine FVIII-BDD is functional and does not induce an immune response in HA dogs. (A) WBCT after 3 injections of cFVIII-BDD in an HA dog (mean ± SD). The WBCT shortened within 5 minutes of the protein infusion from more than 45 minutes (baseline) to 13 to 16.5 minutes (normal range, 8-12 minutes). (B) FVIII antigen and clotting activity after intravenous injection of cFVIII-BDD. For one protein infusion of the same dog, cFVIII activity was determined by Coatest assay and antigen levels were determined by enzyme-linked immunosorbent assay specific for the cFVIII heavy (HC) or light chain (LC). The Coatest was performed using purified cFVIII as a standard. One unit is defined as 100 ng/mL. (C) Monitoring antibody and inhibitor formation to cFVIII-BDD in HA dogs. In addition to the adult dogs, neonatal naive animals that had not previously been exposed to normal canine plasma were treated with cFVIII-BDD. IgG represents both IgG1 and IgG2 data.