Adorable pup! Congrats on getting such a cutie! I had a 45 lb cocker spaniel, all muscle, that pulled me like a bull on the loose and loved to run full speed on the leash. I kept the end of the leash on my right wrist to hold on to her. I never changed to a harness or forced her to stop but I should have. Eventually the pulling damaged my right wrist resulting in some temporary damage, separation and swelling inside the wrist and excrutiating pain and several cortizone shots to see if that would heal it. If the cortizone shots hadn't allowed it to heal the doctor wanted to do surgery. That's when I forced her to stop. Luckily the shots and stopping her from pulling on me allowed it to heal. Took a few months though.