Does anyone know why my lab slides against the wall like a cat? He does it every single day and has since we've gotten him, and I just can't figure it out. I don't know if he's scratching himself or if it's a lab thing -- anyone else ever seen this? It's always the same wall, so our white hallway now has a lovely brown stripe across it!

My 5 year old staffie does exactly the same, rubbing herself along the wall. The only thing I can think of as to why, is as its their own way of marking out their territory throughout the house.
Sorry I can't shed any more light on as to why!