Not all online casinos have Red Dog for their players to play. That's because not all casino game software creators make this game. Below you will see some screenshots that I have taken of the Red Dog software that each of the listed software providers offer.
Casinos that use RTG, Vegas Tech and Rival will generally accept bets from customers in the United States. Casinos that use Cryptologic, Microgaming or Playtech will not accept bets from players in the U.S.

RTG has the spirit of the game of Red Dog. I love the statue of a dog that they use as the marker for the payout of the hands. The table itself is a little more basic than some of the others on this list. Still, what do you want? It's a pretty basic game.
One very important note: you can only play Red Dog on the download version of the casinos software. RTG currently doesn't make a flash version of Red Dog.
If your looking for a good Real Time Gaming casino, give Bodog or Rushmore a try. They are both excellent and have a great variety of games.

The quality of the red dog game that Rival has produced is very good. I've always been a fan of their games. But come on! You have to have a red dog somewhere on the screen. The word "dog" is in yellow!
Take a look at all the others, you can't help but see red dogs everywhere. The flag marker is brutal, what am I about to lay up my golf shot?
Once you get past the lack of aesthetics, give This is Vegas a try (especially if you like playing slots)

Leave it to the Europeans to come closer to reproducing the experience you would get at a real casino. It is one of the reasons I like some of the foreign casinos better at times.
As you can see, the entire spread table is there along with spaces for other players. Now the other spots are just for show, but at least it gives you the elusion.
The two best Cryptologic casinos are definitely InterCasino and VIP Casino. Both of them are owned by the same parent company.

Microgaming has been my favorite casino games provider for a little while now. They have several hundred different games, much more than most of the others on this list. Microgaming did an excellent job with there version of the game.
Of course, I am going to be a little biased since Royal Vegas uses Microgaming and I'm using their red dog flash game on the site. Also, another UK online casino giant 32Red uses Microgaming software.

Last but not least is Playtech. The best Playtech casino hands down is Golden Palace. This is the first online casino that I played at way back in 2002. I wish I could still play their because they offer multiplayer tables where you can chat with others while you are all betting. I'm not sure if they offer a multiplayer Red Dog table, but they certainly have this feature with many of their games.

I really like most of the other table games that Vegas Technology has to offer. But I really can't say that I'm that impressed with their version of Red Dog. I mean the wrinkled red dog is the closest any of them come to using Clifford, but this looks nothing like a Red Dog table that you would find at a casino.