There isn't going to be really an automated way of doing this. Animation in Photoshop is very simple. You can basically animate just position and scale (also Layer Effects, but that generally isn't as helpful). You could, of course, hand animate this by drawing each individual frame like traditional animation. Each frame of animation would be a separate layer and you could animate the layer visibility. Or you could draw the last frame of blood flow on one layer and animate a mask that slowly reveals the blood trail.