Co-ownership of your puppy should mutually benefit both parties. It’s prudent to enter this relationship with a contract that details where the dog lives and for how long, who pays veterinary costs and health screening tests, who pays event fees, who makes decisions, who does the whelping and puppy raising and when the co-ownership ends. An arrangement where the buyer pays all the expenses and the co-owner makes all the decisions is an example of a one-sided relationship and is one to avoid.