Yes, the purpose is to make the viewer uncomfortable, but then to get them to think about why. You have what looks like blood and the implication that there is a cat in the box and that one is connected to the other. We assume there is a bleeding or dead cat in the box, even though we don't know that for sure. Its Schrodinger's classic thought experiment except in Schrodinger's experiment the assumption is that there is a cat in the box, but you can't know whether or not it is alive or dead. In this case, I would take it further and question whether or not there is even a cat in the box.
At first glance it might seem that way. But the thing about this piece is that Schrodinger's principal still applies. Even with the trail of blood coming from the box, the cat is still simultaneously alive and dead. At least until you open the box to find out for sure.