After the dog had been with us for about 6 months, one of our cats decided he wanted to claim the dog's crate/bed - and Sascha wasn't about to try to tangle with Punkin-Head Jones, the curmudgeonly cat. So in the middle of the night, poor Sascha had to sleep on the (carpeted) floor because somebody else was in her bed.

It only lasted a few weeks; I wasn't sure whether it was a sign of dominance from the cat, or finally, a sign of acceptance for the dog!