United allows domesticated cats, dogs, rabbits and birds to be carried in the aircraft cabin on most flights within the U.S. An in-cabin pet may be carried in addition to a carry-on bag and is subject to a $125.00 service charge each way ($250.00 for roundtrip travel). For travel exclusively on United Express by Silver Airways, the in-cabin pet service charge is $50.00 each way ($100.00 for roundtrip travel). Pets can be booked online or by calling United Reservations for assistance.