Stop Leash-Biting

1. Why Do Dogs Leash Bite - Boredom

One of the most common reasons for leash biting is boredom. Overexcited dogs and puppies want to go everywhere, smell everything, and meet everyone at top speed. When they are forced to walk for long periods of time in a heel position, they get bored and may start biting or playing with the leash. I would go a little stir crazy too if forced to walk in a fixed relative position, with my head looking forward at all times, and a strict no-exploration rule.
To stop a bored dog from leash biting we simply make the walk more FUN.

• Give our dog a job to do while walking.
  For example, let him carry a toy or a stick. This makes things more interesting for him, and also prevents him from biting on the leash.
• Do footwork training with our dog while walking. Take some short breaks during our walk to do do some fun footwork obedience commands such as Jump, Spin, or Weave. This breaks up the walk with an interesting activity and also trains the dog to attend to us when he is outside. I sometimes also do speed and direction training with my dog during our walk. I change speed or direction and get my dog to follow me.
• Play a fun game with our dog. A fun dog walking game is Find-It. I start by calling my dog's name and showing him I have a piece of food in my hand. Then I toss the food a very short distance away and say Find-It. When he finds the food, I praise him and repeat. Once he understands the game, I start making it more challenging by tossing the food farther away, or tossing it into grass or under a bush.
• Stop and smell the roses. Every few minutes stop and let your dog explore all the good smells while you mosy along.  Then, put him back by your side to properly walk again.  I use a release word to let my dog know it's okay to go and mark territory, it's 'FREE'.  Then I simply say 'dogsname heal' with a light pop to let her know to come back to heal position.  This is repeated many times through out the walk.  It gives you more control over your animal which is important when other dogs or instances you can't control come up.

A more interesting walk is more enjoyable for the dog, and for us as well!

2. Why Do Dogs Leash Bite - Over-Excitement

Another common reason for leash biting is excitement. Usually, this occurs when a dog sees a squirrel, cat, or another dog. Instinctually, the dog wants to chase the squirrel or cat. When the dog is prevented from chasing, all that excited energy must still go somewhere, so it frequently gets redirected onto the leash.
A good way to stop this type of leash biting is to stop it at the source. In particular, we want to catch it early and stop our dog from obsessing over the trigger object whether it is a squirrel, cat, dog, or something else. This is one of the reasons why some trainers suggest walking your dog in a perpetual heel position.
Instead, I stay vigilant and redirect my dog's attention back to me as soon as I spot a squirrel or a cat using the dogs name and possibly a treat.  I don't give it right away, I just use the scent to redirect attention by putting it in front of his nose.
Just make sure you stay calm while the dog is over-excited

Once the dog is in a strong state of over-excitement and fixated on an animal/object,  it is no longer possible to redirect the dog's attention away from the squirrel or cat.
When in such a situation, I find that it is best to move away briskly and bring my dog along with me encouraging the attention on me/treat/etc.  Then you have to try again once they have calmed down!

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