In Animal Shelter, there is a shop icon on the computer, which can be used to buy items. It is a shop that gives the player everything that they need to run a successful animal shelter, such as toys, food, water, expansions, new builds, furniture, decor, medication, etc.
The better reputation the shelter has, the more quality items gets unlocked. The player commences with the basic food and water and toys, and while they progress in the game, they get better quality items unlock for them which makes it a bit easier to run a full shelter.