Southwest Airlines Dog Travel in 2026: Fees, Carrier Size, Routes and Rules

Southwest Airlines dog travel means flying a small, vaccinated dog in the cabin of a Southwest domestic flight. The dog stays in a carrier under the seat in front of you, and you pay a one-way Pet Fare. As of October 2026, Southwest charges $125 per carrier each way on U.S. mainland flights and $35 between the Hawaiian Islands. Dogs must be at least 8 weeks old. Southwest does not carry pets in cargo or on international itineraries, and it does not fly them to or from Hawaii.

This guide is based on Southwest's own help pages, its Contract of Carriage (58th revision, effective September 24, 2026), and federal guidance from the Transportation Security Administration (TSA), the U.S. Department of Transportation (DOT), and the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA APHIS). Airline pet rules change often, so check Southwest's pages again before you fly.

What is Southwest Airlines' pet policy for dogs?

Southwest's pet policy page, checked in October 2026, says the airline welcomes "small, vaccinated domestic cats and dogs in an appropriate pet carrier in the cabin on domestic flights." Southwest Airlines Co. sets these core rules:

• Cabin only: "No pets are transported in the cargo compartment" (Southwest pet policy, 2026). If your dog doesn't fit under a seat, it can't fly Southwest as a pet.
• Minimum age: dogs must be at least eight weeks old (Southwest pet policy, 2026).
• One carrier per ticketed customer: each carrier can hold up to two small dogs or two small cats, but not one of each (Southwest pet carrier article, 2026).
• Six carriers per flight: the Southwest Contract of Carriage (2026) says Southwest "reserves the right to limit the number of pet carriers per flight to six (6)," accepted first come, first served.
• No unaccompanied minors: children traveling as Unaccompanied Minors can't bring a pet (Southwest pet policy, 2026).

Southwest doesn't publish a weight limit for the dog. What decides eligibility is the carrier: it has to fit under the seat, and your dog has to be able to stand up and turn around inside it. In practice that means toy and small breeds.

How much does it cost to fly a dog on Southwest?

Southwest's Optional Travel Charges page lists the one-way carry-on pet charge as $125 per pet carrier on U.S. mainland flights and $35 per pet carrier between the Hawaiian Islands (Southwest Airlines, 2026). The fee is charged per carrier, not per animal. Two small dogs sharing one carrier pay one Pet Fare, and a round trip costs two Pet Fares.

Southwest's pet policy (2026) says the Pet Fare "must be paid at the Southwest ticket counter with accepted credit cards" and that it is refundable if you cancel your reservation. The same fee page lists a Southwest-branded pet carrier for $58. Southwest notes that Pet Fare pricing "is subject to change at any time," so confirm the amount close to your travel date.

Southwest pet carrier size requirements

According to Southwest's carrier article (2026), an acceptable carrier must be designed specifically as a pet carrier, be leak-proof and well ventilated, and stay within these dimensions:

Southwest recommends a soft-sided carrier because under-seat space varies by seat type and position on the aircraft, and it warns that space "may be more limited in certain seat types, including aisle seats" (Southwest, 2026). The carrier counts as either your personal item or your carry-on bag. That means you can bring the carrier plus one personal item, or the carrier plus one regular-size carry-on.

Where can my dog fly on Southwest?

Destination is where Southwest dog travel most often catches people out. Southwest's destination article (2026) sets three limits:

1. Hawaii: pets are not allowed on flights to or from Hawaii, but they are accepted on flights between the Hawaiian Islands. The Contract of Carriage (2026) also says no pets are accepted on itineraries between the continental United States and Hawaii.
2. International: "Pets are not allowed on international flights or any itinerary that includes an international flight" (Southwest, 2026). This rule covers the whole itinerary, so a domestic leg booked together with an international one also rules out the pet.
3. Puerto Rico: Southwest says only that "specific requirements may apply." Puerto Rico's Department of Agriculture import rules (updated November 2024) require an official veterinary health certificate issued by an accredited veterinarian and valid for 30 days. Dogs over four months old need a rabies vaccination given within six months before shipment, external parasite treatment within 72 hours before entry, and official identification (a microchip or a collar with a metal tag).

Do I need a health certificate to fly my dog on Southwest?

Southwest's pet pages ask for a "vaccinated" pet, but none of the Southwest pages reviewed for this guide lists a health certificate requirement for flights within the mainland. The rules that apply usually come from your destination. USDA APHIS says it "doesn't regulate the interstate movement of pets by their owners" and that "domestic movement requirements are set by the receiving State or Territory" (USDA APHIS, page last modified June 2026).

Sources disagree here. The third-party guide PetTravel.com (last modified December 2025) says a health certificate is "recommended but not required for domestic flights," while Southwest's own pages say nothing either way. PetTravel.com also lists maximum carrier dimensions of 18.5 × 13.5 × 9.5 inches, which don't match the 18 × 10.5 × 10 inches on Southwest's current carrier page. Where the two differ, follow Southwest. Treat the destination state's rules as binding. Carry your dog's rabies certificate and vaccination record, and ask your veterinarian whether your destination requires a certificate of veterinary inspection.

How to book Southwest Airlines dog travel: step by step

1. Measure your dog and carrier. Check the carrier against the 18 × 10.5 × 10 inch limit, and make sure your dog can stand and turn around inside it.
2. Book your own ticket, then call Southwest to add the pet. The Contract of Carriage (2026) says pet reservations "can only be booked by calling Southwest." The help page phrases it more softly, recommending you reserve "in advance by calling us." Because of the six-carrier limit, call early.
3. Choose an eligible seat. With assigned seating now on Southwest flights, pick carefully. Pets may not sit in an exit row or the first row (bulkhead), and the Contract of Carriage (2026) bars seats with no under-seat stowage in front.
4. Check your destination's rules. Use the USDA APHIS state-to-state page and your destination's state animal health official. For Puerto Rico, follow the Department of Agriculture requirements listed above.
5. Arrive early and check in at the ticket counter. Southwest requires you to check your pet in and pay the Pet Fare at the airport ticket counter before going to the gate (Contract of Carriage, 2026).
6. Clear TSA screening. The TSA says to "remove your pet from the carrying case and place the case through the X-ray machine," then carry the pet through the metal detector (TSA FAQ). Never put your dog through the X-ray machine.
7. Keep the dog in the carrier from the gate onward. Southwest requires the pet, "including head and tail," to stay inside the carrier in the gate area, during boarding and deplaning, and for the whole flight.

What happens at the airport and onboard

Security screening

TSA guidance from Washington Dulles International Airport (February 2023) says pets should come to the checkpoint in a hand-held carrier. An officer may swab your hands for explosive traces. If your dog is likely to bolt, you can ask to be screened in a private room. In that case you're escorted there with your pet still in its carrier.

Pet relief areas

Southwest's airport article (2026) says pet relief areas are available at every location it serves, but "we will not hold a flight for you to take your pet to a relief area." On connecting itineraries, plan relief breaks around tight connections.

Onboard rules and behavior

According to Southwest's onboard article (2026), pets must never occupy a passenger seat, and carriers stay stowed under the seat in front of you. A dog that scratches, barks or whines excessively, growls, bites, lunges, or urinates or defecates in the cabin or gate area may be denied boarding. The Contract of Carriage (2026) adds that if a pet becomes ill in flight, "oxygen or other first aid procedures will not be administered."

Service dogs vs. pets on Southwest

Trained service dogs are handled differently from pets. Following the U.S. Department of Transportation's final rule published in the Federal Register on December 10, 2020, Southwest announced that from March 1, 2021 it would accept only trained service dogs and would no longer carry emotional support animals (Southwest press release, January 2021).

• No Pet Fare: the Contract of Carriage (2026) says trained service animals travel with a qualified individual with a disability "at no charge."
• DOT form required: you must present a completed U.S. Department of Transportation Service Animal Air Transportation Form. Under DOT rules, it must be dated on or after the date you bought your ticket.
• Emotional support animals travel as pets: Southwest says emotional support animals, therapy animals, and service animals in training "may qualify to travel as pets," which means they're subject to the carrier, fee, and destination rules above.

Southwest dog travel compared at a glance

Southwest pet rules vs. Animal Passport: not the same thing

Readers sometimes search for an "animal passport" when planning airline travel, so here is the difference. No Southwest rule requires or accepts a digital animal passport. The documents that count for Southwest dog travel are your ticket, the Pet Fare receipt, your vaccination records, any health certificate your destination state or territory requires, and, for service dogs, the DOT form.

Animal Passport is a separate product. It's a digital animal and livestock passport built on muzzle biometrics, using the fact that a nose print is unique, like a fingerprint. With a phone, a farmer captures a record that links the animal to its owner, breed, estimated age (from a dental photograph, with a confidence score), body condition score (1 to 5, from a side-profile photo), and vaccination history. It was used during livestock flood rescue in Pakistan in August 2025, so farmers could reclaim animals after paper tags washed away. Animal Passport is not a government-issued travel document, not an EU pet passport, and not a substitute for any airline or state veterinary paperwork. You can read more livestock identification coverage on the Animal Passport blog.

Practical tips for a smoother flight

• Practice with the carrier first. TSA advises getting your pet used to the carrier in the days before the trip (TSA, 2023).
• Avoid aisle seats if you can. Southwest says under-seat space may be tighter there.
• Bring a credit card. The Pet Fare is paid at the ticket counter with accepted credit cards.
• Keep paperwork on paper and on your phone. Rabies certificates and destination health certificates are easier to show when they're printed.
• Look elsewhere for larger dogs. Southwest has no cargo option, so a dog that won't fit an 18 × 10.5 × 10 inch carrier needs another airline or ground transport.