Harry loves cardboard too. He'll sit with the inner-tube of a kitchen roll and nibble at it.
There are other uses for the inner tubes of kitchen rolls. They're brilliant for making "woo woo" noises through, the reaction of the hounds is so funny - heads cocked to one side as they try to figure out what the noise is.
dave and daisy haven't got the hang of cardboard tubes. however, dave just lurves receipts..... neil keeps his petrol ones for his tax return. well, he would if dave didn't shred them. just dunno what the attration is !