Initially not all dogs are familiar with the leash. The first step is to get your dog familiar with the leash. Whenever you picked the leash your dog thinks that you tie him up so that he behaves abnormally. After attaching the leash let him run around. After some days he will familiar with leash and additionally helps to own another dog around to have interaction whereas the leash is on. Some dogs are refuse to walk when you attached the leash in that condition you go some step away and call him. You can use the treat for calling him, every successful attempt you give him treat and be patience do not hit him.