Slinky the space dog (Butch), Doom machine (Sam), Baby puppy (The Russian)
Lou first appears as a puppy along with other beagle puppies in a farm. While all the other puppies seek a comfortable home, Lou seeked adventure. Lou tries to jump out the window but fails, and his Lou's siblings laugh. Soon, D.O.G. sends in agents to get a home after recieving the news the Brody family was adopting a puppy there.
When Lou was picked due to a mistake, Butch was sent to train him and partner with him.
In the end, at a Christmas tree factory, he defeated Tinkles and chose his family over being an agent. Surprisingly, he appears as leader of D.O.G. in the second film.
Lou has become head of D.O.G. and wears an office uniform for dogs. He also has a mate.
- Lou is mated and has puppies.
- We can assume he lives with his mate. We can assume this because he says in the second film "my wife is at the groomers."
- The statement above may also show he still lives with the Brody family, as who would take his mate to the groomers.