Kenmore QuietGuard Dishwasher makes squealing noise when draining?

I have a Kenmore model #587.1415400 built-in dishwasher that makes a loud squealing noise while draining. The unit came with the house we purchased, and I do not know the history of the dishwasher, or who installed it. The Service Data Sheet (found in the door) indicates that the drain hose should be mounted at a minimum loop height of 32" to ensure proper drainage. However, it appears that my unit is exhausting directly into a floor-mounted drain, and it appears to not have the rubber drain hose. Is it possible that the water is being syphoned out of the dishwasher during use, and that the drain pump has been running dry?