Leasing comes in two main varieties: share-boarding and full leases. With share-boarding, the owner leases his horse out to a lessee for riding on certain days each week. Full leases allow the owner to lease the horse completely and the lessee can ride the horse every day. The leasing fee normally covers the horse's monthly board, shoeing, and routine veterinary care. With share-boarding, the cost to lease will be about half that of a full lease. If the horse becomes seriously ill or injured, typically the owner will be responsible for the horse's veterinary bills.
For more information, please read the story How to Lease a Horse.