The odor was there when we moved in last year. It seems most distinct in the areas where we have a particular plush carpet,ie.,in the living room/dining room (first floor),stairway, and second floor hallway. We really don't think it's an animal. When we get on our hands and knees to actually smell the carpet we don't really detect the source. The odor is particularly obvious when entering from outside after the house has been closed up without air conditioning on a warm day. Help!!