How To Stop Guarding Behaviours?

[Penel]

Lol it might be easier to come over and show you  

I would use two high value toys - as opposed to different value toys.
When are you getting the treats out - he is bound to drop the toy and leg it back to you if you are showing him the treat.... *only* get the treat out when he has brought back the toy.

[Rachel B]

We had similar problems with Barney (and still do to be honest).  Once we had two soft-ish balls and we threw one, and he came bounding back with it, i threw the other and he took teh first ball with him and when he came back he had both balls in his mouth!!  

I thought...i know i'll out-trick you so i threw a third ball, and off he trotted with teh two original balls...but when he came back he had none.  He had taken all three balls to his crate!!!

[Wendy G]

Hi Denise
Sorry my ideas didnt work for you.Does it matter if he does not retrieve?.
Do you need it for dog training,not being facetious but I have not been to training classes (only Gundog) when you certainly need a retrieve.My old dog Murphy a Worker( sadly no longer with us) ,would not retrieve as a puppy .he would sit and stay while I threw the dummy and mark it every time,when I sent him for it he would go off smartly straight to it but would not pick it.As I go beating and not picking up I didnt worry about it. Then out on a shoot when he was about 2 years old, beating in a wood he returned to me with a pheasant in his mouth which he had seen fall after being shot,after that he picked any sort of bird and his retrieve was no longer a problem.So it does happen that they are late retrievers.Perhaps it would be best if you left it for a while  and go back to it at a later date.
Good Luck