In the park there are 6 different packs. Previously you could have 3 dogs with 3 different packs. This has today been changed, and all the dogs on your user will get the same pack.
The packs have their own special room, with its own shop that only those with the same pack as you have access to.
The packs are getting a remake/redesign, so therefore the shops in there are empty right now. But all the rooms will change and things will happen in the future.
During the evening of July 10, all dogs on the same user were given the same pack. This is chosen at random based on the packs the dogs already have, so you can not ask for a specific pack. New dogs you make on the same user will of course also have the same pack.