Most airlines generally do not have restrictions for cats and dogs, but often restrict the other types of animals that they allow. Most airlines allow domestic birds in the cabin, but may have restrictions against poultry or birds of prey. Most airlines will only allow reptiles, amphibians, fish, and invertebrates to fly as checked luggage or cargo; some airlines will allow rabbits and other small mammals in the cabin, but others restrict them as checked luggage or cargo. Primates, with the exception of service monkeys, are generally restricted from the cabin.
Most airlines also have restrictions about the maximum number of pets that they will allow on any flight, so you will want to book your pet's ticket when you book yours. If you will be carrying your pet into the cabin, you will have to pay a pet fee, and your pet's carrier will count toward your carry-on luggage allowance. (If your pet will be flying as checked luggage or cargo, you will also have to pay a pet fee, but your pet's kennel will generally be considered in addition to your luggage allowance.) If you do not inform the airline in advance that your pet will be flying, your pet may not be allowed on the flight if the maximum number of pets has already been reached, or you may have to pay an additional fee.
All airlines have restrictions for flying in extreme temperatures, although the actual temperature ranges do vary slightly from airline to airline. If at any point in your journey, your airplane will be in a city where the temperature is forecasted to be less than 45 or 50 degrees F (7 or 10 degrees C), you may be required to present a Certificate of Acclimation from your veterinarian, attesting that your pet is accustomed to low temperatures. If the temperature will be less than 10 or 20 degrees F (-11 or -12 degrees C), your pet will not be allowed to fly as checked luggage or cargo.
