Does frontier airlines allow pets are accepted on Frontier Airlines. Please note that only small dogs, cats, guinea pigs, rabbits, hamsters, and housefowl that fit in a carrier beneath the seat in front of you are allowed in the cabin. The pet must spend the whole flight inside the container. Pets are not allowed on international flights, and there is a one-way cost. Pets are not permitted to fly as cargo or checked luggage on Frontier Airlines. Service animals can travel free of charge as long as they follow the airline's policies.