Famitsu checked out Grand Theft Auto V recently and the big news from their coverage is that you can customize your dog. The dog's name is Chop, and you can give him different color collars, other accessories, and more. There's also the danger of losing Chop, so you're going to have to keep an eye over him.
Other bits of info from Famitsu include how each of the three main characters have a unique walk animation, there will be at least one underwater mission, and that there are 15 types of wild animals that can be found in the game. As for release, Japan will get GTA V on October 10, 2013 for the Xbox 360 and PlayStation 3.
Hopefully managing Chop won't be too much of a chore. If anything, I'd like it to be like the horse system in Red Dead Redemption. Whoops you just shot your horse in the face by accident? Whistle for a new one!