Well I won't write off his interest just yet as he is still surprising me.. We have had a heatwave and the river is low. Today he amazed me by paddling around (previously he wouldn't even dip a paw in water). Then he doubly amazed me by picking up a stick and playing with it. Ever since my old dog got a stick injury, I haven't encouraged it but it was nice to see.
None of this would have happened if I had had the ball because once he knows it's there, he is totally fixated. I can't get away with hiding it either because he can smell it