I have a 5 month old Australian Shepherd mix. We used to play fetch without a problem but since I returned from my trip, he will run off with toys and play by himself. He will not bring toys back to me. I have tried all sorts of toys which resulted in a sea of his toys around "his" spot in backyard. He will come when called, but will drop the toy and treats don't work either. Sometimes he will bring a toy back to someone else when I throw it. Any suggestions?
This is a bit tricky - your dog may have just gotten used to playing moreso on his own while you were gone. Hopefully we can solve the problem though!
First off, try teaching fetch as a new game, start all over with playing it. However you taught him to play the first time - do it again! Nothing like starting from square one to retrain something
Second, try starting with very small distances for your dog to bring the toy back. Just chuck it slightly out of arms reach, so that you can hold your arm extended to indicate you want the toy back. Once he responds well to this, chuck the toy a bit further and further and see how you go.
Its a bit tricky since he seems to just drop the toy when he comes back to you - try to call him immediately after he gets the toy you've thrown. It may help to keep another toy in your hand so he's just excited to come back to you and may not drop the other toy so readily. I think this in combo with only throwing very small distances at first should help the situation.
You could also try playing with another friend. Given he won't be returning the toy to who threw it, but its another stepping stone to getting back into proper fetching. Be sure to praise him so so much when he does bring a toy back to anyone (good boy, fetch!). Use a command word (fetch, whatever else you may use) when you throw and when he does return a toy - dogs learn well when they can associate a verbal command with a correct behaviour.
Hopefully these suggestions make sense and help you get back on track. Keep us posted, please, on what happens!