Of course, animators use real life references more often than not, but River belongs to Level Designer Joel Burgess, so the dog spent a lot of time in the office, running around doing dog stuff.
— Joel Burgess (@JoelBurgess) June 15, 2015
— Michelle Burgess (@MichelleBurgess) July 8, 2015
Todd Howard said that it was important for River to be around the office, in order to help the team with animations and behaviors. One of these according to Todd is that whenever the player is doing something, the team wanted to know how Dogmeat should respond. They also showed a reel of River doing dog stuff like catching frisbees and running around the office… for reference material of course.