Why does my dog hate my husband?

Why does my dog hate my husband?

She said they had their dog, Dawn for close to three years and that the Dawn has hated her husband for almost that entire time.  She described Dawn as growling as soon as her husband pulled into the garage, and then Dawn would bark at the husband when he entered the house. After a few minutes, Dawn would finally slink off into a bedroom and avoid her husband.  The clients were at their wits end and not sure they could continue living with a dog who seemed to hate the husband.