Did you train him on leash walking at all?
It takes a while before a puppy will get the message that the leash is something that is not hurtful or a chew toy
To train them you have to put the leash on let them walk around with it on to get the feel of something being attached to the collar
start picking up the leash without pulling on it
then slowing start picking it up and lightly direct them places
this will take a few sessions
Mine right now are still thinking that they are great for chewing
