Nintendogs uses the DS' touchscreen, where the owner can: play with, train, pet, walk, brush and wash a virtual dog.[6] The game also utilizes the built-in microphone, where the player can call their puppy or teach the puppy tricks.[7] Money can be earned by placing in competitions or selling items at the secondhand shop and can be used to purchase supplies, puppies and home decor. Dogs can be walked and can be taken to the park where they can practice disc catching skills for disc competitions and to the gymnasium to practice dog agility for agility trials.[6] While walking, question mark icons on the map point out areas that may contain neighborhood dogs or presents, though presents can be found unmarked as well.
Only three dogs may be kept at the player's house at one time and up to five dogs can stay at the dog hotel, where dogs can be swapped, dropped off and picked up at any time. The player can also choose to part ways with a dog by donating a dog to the hotel.
As time passes without the dog being cared for, its condition will slowly deteriorate as it becomes more hungry and dirty. The condition of the player's dogs can be found by clicking its name. Hunger is listed as: Full, Normal, Hungry and Famished. Thirst is listed as: Quenched, Normal, Thirsty and Parched. The condition of the dog's coat is listed as: Beautiful, Clean, Normal, Dirty and Filthy.
Nintendogs features a variety of contests, which are the player's main method of earning money and trainer points. There are three contests Disc Competition, Agility Trial and Obedience Trial. In each of them, there are 5 classes: Beginner, Open, Expert, Master and Championship. Each contest is commented on by two men, named Ted Rumsworth and Archie Hubbs. If the player's dog places 3rd or higher in its class, the dog will proceed to the next class, where the contest increases in difficulty level. Prize money earned differs depending on which contest has been entered, what place is finished and the class the dog is in. If the player does not place in the top three, they will be dropped to the previous difficulty level.[8]
Nintendogs allows users to communicate wirelessly to other Nintendogs users through Bark Mode.[9] Before activating Wireless Mode, the player can choose to give the other user a present.[10] When another user with Bark Mode activated is nearby, the player will have an opportunity to play with the other trainer's dog and if the user has recorded a voice message on their White Record, the other user will hear the voice message.[11]
Dogs do not die, have puppies or age (meaning they remain as puppies).[12]