Harness for me every time. When they suddenly go into 'launch mode' having seen something to chase, the impact on the poor dog's neck and spine must be enormous. It makes sense to get something fairly cheap while the pup is growing as you will be changing it several times. Once your pup is fully grown have a look at the Ruffwear harnesses. Not only are they 'Houdini proof' but they also have a handle on the top to lift them safely over obstacles or out of trouble. A lot easier than hugging a wet and muddy cocker while you lift them over a wall or a gate.
