In case there was ever any doubt, Fallout 4's Dogmeat is based on a real dog. The dog's name is River and he or she (it hasn't been made clear) belongs to one of the game's developers, lead level designer Joel Burgess.
In a presentation at QuakeCon 2015, Fallout 4 creative director Todd Howard said that River spent a lot of time at the Bethesda offices to help the team get a feel for the dog's animation and behaviorial tics.
According to Howard, that whenever the player character was performing an action, the team wanted to figure out what the dog was doing as well.
The presentation goes on to show River chasing frisbees and running around.
Burgess and his wife Michelle also posted tweets of River comparing them to Dogmeat. You can see River below.
— Michelle Burgess (@MichelleBurgess) July 8, 2015
— Joel Burgess (@JoelBurgess) June 15, 2015