Things You'll Need
Instructions
Insert the Action Replay cartridge into your Nintendo DS. Make sure you hear it "click" to ensure it locks into place.
Insert the Action Replay CD into your computer's disc drive. If you haven't already installed the software on your computer, you'll need to follow the step-by-step installation instructions on your computer screen first.
Connect your Nintendo DS to your computer with the USB cord that came with the Action Replay cartridge. There is a port for the USB cord on the back of the Action Replay cartridge.
Turn your Nintendo DS on and wait for it to load.
Open the "Action Replay Code Manager" on your computer.
Go to "My Subscription" and click on "CodeJunkies US" if you are a US player. Otherwise, click on the version that corresponds to your location.
Select "Nintendogs: Dalmatians and Friends" from the list of Nintendo DS games in the "My Subscriptions" window to show all of the available action replay cheats. You're looking for the size modifier cheats known as: flea-size dog, tiny dog and small dog.
Drag these cheat codes to the "Nintendo DS" area of the screen. The codes will automatically transfer to the Action Replay Device and be available the next time you play the game.