An acclimation statement or certificate may be required by an airline. The statement or certificate, signed by the veterinarian, will waive the Animal Welfare Act low-temperature federal regulations for animals traveling in the cargo hold. Airline requirements regarding acclimation statements or certificates vary. Check with the air carrier to determine requirements. Acclimation statements or certificates are often required if the pet is traveling in the cargo hold and temperatures at the departure or destination airport are at or expected to be below 45 degrees fahrenheit. However, some airlines will require acclimation statements or certificates even if temperatures are not expected to be below 45°F. Acclimation statements or certificates are written at the discretion of the veterinarian and are based on the veterinarian's assessment of the pet's health and the temperatures the pet is accustomed to. There are baseline standards that the airline must follow and animals will NOT be allowed to travel in the cargo hold when: Temperatures are lower than 45°F (7.2°C), if the airline cannot guarantee that the animal will not be exposed to these temperatures for more than 45 minutes when transporting between terminal and the plane OR for more than 4 hours in the holding facility. Temperatures are higher than 85°F (29.5°C) for more than 4 consecutive hours while in the animal holding area in the terminal, or for more that 45 minutes when being transferred between the aircraft and terminal holding area.