Boot Liners

 Geoff - I bought an excellent liner from a company called Titan Covers.  Bit expensive but they are made to measure for specific cars and fasten around the boot using velcro (the hook bit just sticks to the carpet so no need to stick anything to the car).  They are very good quality, substantially made from a sort of canvas material - washable or wipe clean.  When I bought a new Touareg, almost two years ago, like you, I was keen to protect it from general dirt plus a scruffy mutt and the back of the car still looks brand new.  I would recommend getting the optional extras to protect the bumper and back of the front seats (for when the back seats are folded down) - especially with a dog.  As I said, they are expensive - I think my whole lot came to about £120 but given the price of the car, was well worth it in my opinion.