Upon the arrival of the inbound pack animals or before the departure of the outbound pack animals, the owner or agent shall declare and register the species and quantity of the animals with the Customs. The owner or the agent shall provide a customs-acceptable guarantee or deposit for the inbound pack animals, and ensure that the animals will be transported back; and for outbound pack animals, the owner or the agent shall guarantee for transporting them back to China. After registration, the Customs conduct necessary inspections, and will, upon verification, issue the certificate of registration which approves the entry and exit of the animals; and when the animals are back, the certificate should be handed back to the Customs for verification and cancel (or return of the deposit).