Instructions
Put food in two different-looking bowls. Use the same bowl for the same dog each time. When the puppy or adult dog sees its bowl, the dog begins to identify this as its food.
Place the puppy and adult Chihuahua's food bowl in separate rooms. Make sure at least one of their bowls is behind a closed door.
Put the dogs in separate rooms but feed them at the same time. Close the door to keep the Chihuahua's separate. Allow the older dog to feed for a specific amount of time, such as 30 minutes for up to twice a day, and three times a day for the puppy.
Scold either dog if it attempts to invade the other's dog feeding space. If one dog is in a room without a door, it may attempt to go toward the other dog's feeding space. Although it is unsuccessful because the door is closed, reinforce that the action is not acceptable. Say, "No" and direct it back to its own space.
Pick up the food bowls and allow the dogs to intermingle.
How Do I Keep a Full-Grown Chihuahua & a Puppy Chihuahua From Eating Each Others' Food?
Your Chihuahua puppy has a smaller mouth and different dietary requirements than a full-grown, adult Chihuahua. You don't want either of them to eat the other's food. This behavior will not harm either of them, but it often results in your puppy not having adequate access to proper nutrition as it is bullied out of the way by the larger dog. To keep the other from invading the wrong food bowl, there is something you can do.