Plasma concentrations of factor VIII after administration of DDAVP to conscious dogs

The effect of the vasopressin analogue DDAVP on Factor VIII in plasma has been extensively studied in humans. To examine the effect of new and potentially better analogues a suitable animal model has to be established. In the present study trained Beagle dogs were injected with DDAVP and the time course of the Factor VIII response was monitored by a modification of the chromogenic substrate assay for Factor VIII. In most of the dogs DDAVP caused a biphasic increase of plasma concentrations of Factor VIII with an initial smaller increment within 10 min after the injection followed by a larger secondary rise after approximately 45 min. The average increase in Factor VIII was smaller than found in humans after comparable doses of DDAVP, and a few dogs responded very poorly. Despite these qualitative and quantitative differences it is concluded that trained dogs may serve as a useful model for testing the ability of other analogues than DDAVP to increase Factor VIII.