Southwest Airlines Pet Policy makes traveling with small pets easy and affordable. Only small, vaccinated cats and dogs are allowed in the cabin, and they must stay in approved carriers that fit under the seat. Each passenger can bring one pet carrier for a $95 fee each way. According to the Southwest Airlines Pet Policy, pets are accepted on a first-come, first-served basis, and space is limited. Pets are not permitted in cargo. It's important to check in early and keep your pet in the carrier during the flight. Service animals are covered under a separate policy.