When dogs are biting leashes, don’t let them think of it as a game. Meaning don’t play tug of war with your dog over the leash or drag the dog if they refuse to move. Remember with rescues to not automatically use adversives, there is a much more humane and successful method. If you and your dog our snuggled on your sofa put the leash on your dog but don’t move. Reinforce your dog for wearing the leash with out biting it. If your dog is afraid of leashes this is a great solution. Let your dog wear the leash in the house so they almost forget they our wearing it. Reinforce your dog with love or food through out the process . In time the dog will be desensitized to the leash and you can go on walk comfortably.
If your dog bites the leash in an aggressive away instead a fearful way we need to use a different technique. Ask your dog to sit , place the leash on the dog, and with treat in hand when the dog starts getting excited ask him to sit again . If he sits reinforce him. If he is hyper active and not responding to commands, take leash off and no walk. Come back a few minutes later and do it again. Only go on that walk when they are calm. It is remarkable how quickly dogs improve with this technique. Always reward small improvements. If your dog is more calm after the second approximation take that!!
Dogs are all different and there problems are different. Don’t treat one dogs problem with another dogs solution. Understand your problem and diagnose it properly and use positive reinforcement training .