My 1 1/2 yr. old daschund sleeps in a crate at night and has always done good sleeping 7 to 8 hours a night. Just this last week he has started whining and yipping during the night in his crate. Starts anywhere between 2:00 am to 4:00 am. There has been no change in his routine and I can't seem to figure it out. Thinking maybe it's separation anxiety. Any thoughts?