CSAs.

Pressure time tracings are depicted for a healthy control dog (A) and an affected GSD (B). The CSA measures pressure (mm Hg) in a cassette chamber containing nonanticoagulated blood flowing in plastic tubing. The labeled events include the following: punch = lumen pierced by fine needle; minimum = low pressure caused by blood exiting punch hole; PHT (pressure is restored by thrombi sealing punch hole); postpunch = return to baseline blood flow; CT (luminal flow is occluded by clot). Control dog: PHT = 1.1 minutes, CT = 13.4 minutes; GSD: PHT = 0.7 minutes; CT = more than 30 minutes. The 5 affected GSDs demonstrated a variable number of transient pressure drops in the postpunch period; however, all consistently failed to form an occlusive clot.