There are many chained dogs in communities. Some of these dogs never have interaction with their owners other then at feeding time.
These dogs can become aggressive when left for days or months at a time on a chain. Even if they have a dog house, they need human interaction.
They are very social animals.
When chained, they are bored. They are lonely and feel so out of the loop.
There have been laws passed in areas all over the United States. Do you have one in your area? Is it one that helps the dog?
You can check things out at this website and maybe you can help dogs in your area live off their leash.