Why do dogs pull on the lead?

It can be a number of things including:

• They haven’t been trained to walk on the lead
• They’re excited to get to where they’re going – particularly puppies where the world is new to them
  and they’re eager to experience everything
• They’re trying to be in charge
• Where they’re walking is making them scared or anxious – particularly if there’s lots of traffic or it’s noisy
• They’re eager to get involved with other dogs or people

How to stop dog's pulling on the lead.