7 year old standard poodle

Question
I have had the dog since he was 8 weeks old - when he is let off the lerad for a run on the beach or field anything he can find, balls, paper pieces of old shoe, he recently found an old sock.  He doesn't just chew things he actually swallows them.  We try to stop him but he thinks it is a game and runs off by the time we catch him its too late.  We often dont know he has eaten something until a day or 2 later when he sicks it up.  Why is he doing this? I dont want to muzzle him but I ant think of anything else.

Answer
I think this is one of those questions where there isn't a good answer.  Why dogs do stuff often is quite speculative.  Some dogs are much worse than others about chewing, and few are still so bad at 7 years old.  Many people would say he is poorly trained and you need to train him not to.  Perhaps you could.  I am not going to try to say how.  Perhaps a private trainer or behaviorist would have some ideas.

Eating that stuff is highly dangerous.  I hate the idea of a muzzle, but choking or surgery for an intestinal blockage would be worse.  I am sorry I don't have a better suggestion.