Dog (written as DØg on his body) is Alyx's "pet" robot. Dr. Eli Vance built Dog to protect his daughter, Alyx, when she was young. Dog was originally a relatively small, 1 meter (three foot) high robot. As Alyx grew older, she began upgrading the robot by adding additional parts, and it now towers 2.5 meters (eight feet) high.
-- half life wiki
About this creation
In this moc Dog has many joints; from foot to ankle to thigh all the way to shoulder to finger and even neck.