Our dog Kona, a flat coated lab, has met his first rival. He loves all of the mammals he has met to date. This dog, he will not tolerate. I am not aware of any particular problem. The owner runs the dog on a bike. Every time they pass Kona is pulling at the leash and acting very aggressive. I initially was tense and firm with Kona. I am now trying to be calm to let our dog know I am not worried or concerned about the passing dog. What else can I do to diffuse the stress for our dog?