They do not commonly bleed spontaneously but are at great risk to bleed due to injury or surgery. It is not rare for an affected dog to have minor surgery, such as a neuter, or trauma and to not bleed excessively. Carriers have one normal gene and one mutated gene. This level will vary over time with any given dog and vary greatly between dogs. Carriers rarely bleed except at times of great stress to their clotting system.
Normals have two normal genes.
It should be noted that in the event of a prolonged stress to the clotting system, such as very long surgery or a bleeding ulcer, normal dogs and humans would exhaust their vWF and other clotting factors so that they have a prolonged bleeding time. This is treated with transfusion of platelets and clotting factors. This in no way implies they have vWD or hemophilia but is a normal result of a prolonged bleeding episode. Since this is an autosomal recessive disease, for which we now have a test, and the carrier frequency is relatively low, we have the potential to eliminate this disease from our breed with prudent breeding practices. The carrier frequency is the percentage of all dogs within a breed that carry the gene.