There are two types of items Clothing and Consumables. Clothing can be worn to add stats to your animal but it will wear out over time. Consumables can only be used once during a game and will not carry over the next time you play.
Presents found on the map or after hunting contain costumes or other useful items. Making clever use of those items is critical to surviving.
In Multiplayer, players can use medicine to revive fallen partners.