13 year old sleeps in upstairs hallway. Louis has the run of the house at night. For the last 6-8 months he will pee on the floor in the living room, in the middle of the night. We had carpet until recently removed and sub flooring now until hardwood installation in 10 days. Louis always goes outside right before bedtime. Six months ago I took him to the vet and numerous tests performed and all normal . Vet did give him antibiotics for 10 days just in case he had a UTI. So frustrating! Any ideas on why he may be peeing in the middle of the night ?