my dog will not go for walks

Question
Hi Erica,
I have a male golden retriever who just turned three.  He is a wonderful dog, but we have never done any training with him.  We used to go for walks all the time up until about a year ago.  He pulled on the leash but was otherwise fine.  For pulling, we tried the gentle leader, which worked great.  Suddenly last summer, he just stopped going for walks.  I still continuously try to take him.  This is what happens:  I get his collar (just a regular leather collar), and he is very happy.  He comes to the door, sits, and I put on his collar.  I attach the leash.  He seems perfectly fine and smiling... until we walk out the front door.  He walks out onto the stoop, and then just stops.  He will not move.  He is smiling, but at times it seems like his back legs are trembling.  On occasion, I am able to pull him down the steps or hill to the side walk (which is hard, he is strong, and I don't like pulling him anyway).  That is as far as we get.  He will not leave the perimeter of our front yard.  I have tried driving to a park and walking him (thinking he does not want to leave our house) but he has the same frantic reaction, and pulls me back to the car.  Even with a choke chain he pulls very hard.  I just use a regular thick nylon leash.  He loves to run around in backyards or at the dog park, play fetch... Oh, and recently I drove to another location, and got him going (we both ran)...  then  all of a sudden he would just stop.  And stand.  So clearly, my dog and I need help!  Any suggestions would be much appreciated.  I have even tried luring him out of the door with hotdogs and other treats.  Thank you!

Answer
My first suggestion would be to take him to the vet and see if there is a physical reason for this.  Anything from hearing/vision decrease to an unknown injury could cause this behavior.

Have you tried using a toy/tennis ball to lure him?  If he is comfortable in the front yard, start playing fetch there and gradually cross the perimeter line.  As you get a little further from the house and he is into the game, start increasing the distance.  Even play with his leash on him, so you can smoothly turn the game into a walk without going through the motion of putting on the leash after he is in "fun" mode.