We have 2 dry bags for Boysie. They are great for using in the back of the car (after a muddy walk), and also after a bath or when he has come home wet / muddy. It did take him a little while to get used to it - though it was funny watching him try and walk when he was in it. He is now resigned to his fate when he sees it - as long as he isn't left alone he will settle down nicely for the 20 minutes or so it takes for him to dry. He loves it when he is free again!
The only minor 'problem' we have is with the size- the ones we have are really aimed at Springer size, but the smaller size seemed too small. He does have a fair amount of room to spare!
