Platelet storage pool deficiency in pigs

We report a new bleeding disease--storage pool deficiency (SPD) of platelets--in pigs from the Mayo swine colony of homozygous von Willebrand's disease (vWD) and of heterozygous carriers of vWD. Levels of factor VIII, von Willebrand factor antigen (vWF:Ag), and ristocetin cofactor (RCof) were similar in the vWD carriers and SPD pigs. The latter pigs, however, had bleeding times of 15 minutes or more and were severe bleeders, in contrast to clinically normal vWD carriers. Platelet aggregation in response to collagen was reduced in most SPD pigs. Total platelet content of ADP, ATP, and serotonin was less than that of normal pigs. While the initial uptake of 14C-labeled serotonin into platelets was similar in SPD and normal pigs, retention of serotonin was reduced in platelets of SPD pigs. Transmission electron microscopy showed a large decrease of dense bodies in the platelets of SPD pigs. These findings support a diagnosis of SPD. Genetic analyses suggest an autosomal recessive mode of inheritance. A breeding program is under way to produce pigs affected only at the SPD gene, thus allowing further characterization of SPD and SPD-carrier pigs.