The full cooperation of the mailer is essential in order to safely and effectively transport animals through the mail. The following factors are applied to all shipments of mailable live or dead animals:
- Protection of Postal Service employees and the public against harm from dangerous or diseased animals.
- Protection of the mail and the environment against the following:
- Damage to the shipping container or other mailpieces from either the animal or the refrigerant used (e.g., moisture or condensation from melting ice, or pressure build–up from dry ice).
- Obnoxious odors and noise.
- Protection of animals against death, or protection of animal specimens against spoilage, taking into account the following:
- Expected time in transit.
- Expected temperature in transit (weather conditions).
- Packaging, including insulation against impact, heat, cold, and preventing suffocation.
- Ability of an animal to survive without food or water during transport. Live animals must be transported without food or water, because liquids, moisture, and loose foodstuffs can cause damage to the shipping container, other mail, and Postal Service equipment during transport.
- The ability of the Postal Service to provide transportation and delivery service. Mailers are urged to work with postmasters in providing advance notification of shipments of live animals. The Postal Service advises destination and transfer offices when any significant quantities of animals are moving in the mail. Postal Service field personnel should consider a 4–hour time limit on the period during which animals (especially bees, day–old poultry, and adult birds) may move in a regular, closed Postal Service vehicle.