The dog that befriends Carl and Russell is Dug.
Dug is a Golden Retriever encountered in the wilderness near Paradise Falls. His collar contains a device that translates his thoughts into spoken English, letting the audience hear his eager, affectionate, and often easily distracted personality. He quickly attaches himself to Carl and Russell, despite Carl’s initial reluctance to take responsibility for another companion.
Dug is actually one of several dogs belonging to Charles Muntz, the explorer who is hunting Kevin. The other dogs wear similar translator collars and follow commands from Muntz. Dug’s friendliness and clumsiness contrast with the more aggressive behavior of dogs such as Alpha, Beta, and Gamma.
A common mix-up is confusing Dug with Kevin, the enormous bird Russell names during the journey. Kevin is the animal Carl and Russell try to protect, while Dug is the talking dog who becomes their loyal ally. Dug also appears in Pixar’s 2009 short film Dug’s Special Mission and later stars in the Disney+ series Dug Days.