Chop is Lamar's dog in Grand Theft Auto V. He is a Rottweiler and it is currently unknown how you will be able to interact with him in-game, however a pre-release screenshot reveals that he will be able to sit in a car with Franklin, and possibly occupy a seat like other NPCs. In Franklin's Trailer, Chop is shown to be attacking a Ballas gang member; leading to the conclusion that he can help Franklin during fights. However, it is unknown if other dogs will do the same. Chop can also help the player to find hidden packages. There will be a throwable ball in the character's weapon menu, allowing you to be able to throw the ball for Chop to catch.
It was said in a interview with a Japanese magazine that Chop can run away. If this occurs you need to find him or he could be gone forever. Chop can also be killed in gunfights. This would mean that most other dogs can die as well. Chop can also be customized. Change the collar color to your liking or even give him a bandana if you wish. Unfortunately, this is all unconfirmed and was taken from a source of unknown reliability.