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Bringing Your Pet Aboard Southwest in 2025: A Detailed Walkthrough

Sharing a trip with your four‑legged companion transforms an ordinary journey into a shared memory. Southwest Airlines continues to accept small domestic cats and dogs in the cabin on almost every domestic route, making it one of the most predictable options for travelers who refuse to leave their pets behind. But a smooth experience depends on more than just a cute carrier. Understanding the precise rules—dimensions, fees, paperwork, and in‑flight etiquette—will spare you last‑minute airport surprises. This 2025 guide unpacks every layer of Southwest’s pet program, from booking a space to landing with a content animal. Use it as your pre‑flight checklist, and you’ll walk to the gate knowing you’ve covered every detail.

Which Animals Can Fly Southwest?

Exclusive to Cats and Dogs

Southwest’s cabin pet policy is unambiguous: only household cats and dogs are permitted. The airline does not accept rabbits, ferrets, guinea pigs, hamsters, birds, reptiles, or any other species, no matter how small or well‑behaved. There are no exceptions for miniature pigs, hedgehogs, or sugar gliders. If your animal isn’t a cat or a dog, you’ll need to explore pet‑shipping services or ground transportation. The airline also does not transport pets as cargo, so in‑cabin travel is the sole option.

Age, Health, and Condition Standards

Every pet must be at least 8 weeks old and completely weaned. Southwest requires that the animal be healthy enough to endure the flight without visible distress. Gate agents can deny boarding to any pet that appears lethargic, aggressive, or ill. A veterinary health certificate issued within 10 days of travel is not mandated on every domestic itinerary, but it is heavily recommended. Without current documentation, a wellness concern raised at the counter could end your trip. Always schedule a pre‑flight exam, and carry the signed certificate along with proof of core vaccinations. Even if the airline never asks, the paperwork backs you up.

Brachycephalic Breeds and Heat Risks

Southwest does not ban specific breeds for in‑cabin travel. Nevertheless, flat‑faced (brachycephalic) animals—Persian and Himalayan cats, pugs, bulldogs, Boston terriers, boxers, and Shih Tzus—deserve extra caution. Their shortened airways make them more vulnerable to respiratory distress, especially during warm‑weather boarding when cabin temperatures can climb. While these dogs and cats are technically allowed, you should obtain a frank assessment from your veterinarian before booking. If your pet already pants heavily or struggles to breathe on a hot day, a different travel method or a cooler season might be the safer choice.

Pet Carrier Specifications and Comfort

Exact Dimensions and Construction

The carrier must not exceed 18.5 inches long × 8.5 inches high × 13.5 inches wide (47 cm × 21.5 cm × 34 cm). This measurement is absolute: even a half‑inch overhang can prevent the carrier from sliding beneath the seat. Both soft‑sided and hard‑sided carriers are accepted, provided they are leak‑proof, have a secure floor, and include ventilation on at least two sides. Southwest also insists on a waterproof bottom; most carriers come with a removable fleece pad, but adding a disposable absorbent liner is a smart backup.

Under‑Seat Fit and Smart Design Choices

The carrier serves as your one carry‑on bag. Your personal item must go into the overhead bin. Soft‑sided carriers are almost always the better pick because they compress slightly to fit under seats that narrow toward the aisle or along the window wall. Before travel day, place the carrier under a chair at home and encourage your pet to settle inside for gradually longer periods. This practice reveals any ventilation gaps and helps your animal associate the carrier with calm, not just car rides and vet visits.

A soft‑sided pet carrier tucked beneath an airplane seat, demonstrating correct sizing and ventilation

Ventilation, Entry Points, and Clear Labeling

A top‑opening carrier makes it easy for you—and, if necessary, a flight attendant—to check on your pet without unzipping the entire front panel. All closure points should function securely. To stop accidental escapes in a busy terminal, thread a small zip‑tie through the zipper pulls. Clearly mark the carrier with your full name, a mobile phone number, and your pet’s name. A luggage tag works, but a label sewn directly onto the fabric is harder to lose.

Southwest Airlines Pet Fees for 2025

Domestic Mainland Fare

On all flights within the 48 contiguous United States, Southwest charges a $125 pet fare each way per carrier. The fee covers a one‑way journey even if your itinerary involves a connection, as long as it’s booked on a single reservation. Unlike your airline ticket, the pet fare cannot be paid with points or travel credits. It is also non‑refundable unless you cancel the flight and the pet reservation at least 10 minutes before scheduled departure time and receive a travel credit for the base ticket. After that window, the fee is forfeited.

Inter‑Island Hawaii Fees

Traveling between the Hawaiian Islands on Southwest is a special case. The pet fare drops to $35 each way per carrier. This rate applies only to flights that stay entirely within Hawaii—for example, Honolulu to Kahului. Pets cannot travel in the cabin on any international flight or any route that touches the U.S. mainland from Hawaii, due to the state’s strict quarantine laws.

Payment and Refund Nuances

You pay the pet fare over the phone at the time of reservation with a credit card. If you voluntarily change your own flight, you can generally move the pet reservation to the new itinerary, as long as space still exists. Should you cancel, you must call again to process the refund—don’t assume it will happen automatically. Always ask the phone agent to confirm what portion of the pet fee is recoverable with your specific fare class.

How to Reserve a Spot for Your Pet

Phone‑Only Booking

There is no online or mobile‑app option to add a pet. You must call 1‑800‑I‑FLY‑SWA (1‑800‑435‑9792). This is because Southwest enforces a strict cap of six pet carriers per flight. Reservations are first come, first served, so the moment you book your seat, pick up the phone. Popular routes—especially those to Orlando, Denver, and Phoenix—can reach the limit weeks ahead.

What the Agent Will Ask

Have your flight confirmation number, travel dates, and exact itinerary ready. You’ll be asked for the type and breed of pet, the external dimensions of your carrier, and the combined weight of pet plus carrier. While Southwest doesn’t publish a maximum weight, the carrier must rest entirely under the seat, so a heftier animal still needs to fit the 8.5‑inch height limit comfortably. The agent will collect payment and email a receipt that serves as your pet’s boarding permission. Double‑check that the pet’s name matches whatever you put on any health documents.

When to Book

Ideally, you should add your pet at the same time you purchase your ticket. If your chosen flight is already sold out for pet spots, you may need to switch to an earlier or later departure. Do not wait until the day of travel; walk‑up add‑ons are almost never available on routes with full cabins.

Health Documentation and Veterinary Requirements

Although Southwest doesn’t routinely check health certificates on every domestic flight, the airline reserves the right to request one. A health certificate signed by a licensed veterinarian within 10 days of travel provides the strongest safeguard. It should confirm that your pet is free of infectious disease, external parasites, and is fit to fly. Proof of current rabies vaccination is mandatory for dogs entering Puerto Rico, and it’s also a wise addition for any itinerary. If your destination state requires a specific certificate—some do—bring that as well.

Managing Medicated or Chronically Ill Pets

A pet showing signs of illness—vomiting, diarrhea, open wounds, or constant coughing—will be denied boarding. If your animal has a well‑managed chronic condition, bring a letter from your veterinarian summarizing the diagnosis, treatment plan, and a statement that air travel poses no undue risk. Sedation is almost never recommended. At altitude, sedatives can depress respiration and heart rate unpredictably. Instead, work with your vet on non‑drug calming strategies in the weeks leading up to the trip. The American Veterinary Medical Association offers detailed guidance on traveling safely with your pet, including the risks of sedation.

Ticket Counter Check‑In

Pets cannot be checked in at a kiosk or via curbside service. You must visit the full‑service ticket counter. The agent will verify your government‑issued ID, confirm the pet reservation, and inspect the carrier for sturdiness, leaks, and size. You’ll receive a pet cabin tag that must stay on the carrier until you exit the destination airport. Arrive at least 30 minutes earlier than you normally would to absorb this extra step.

TSA Security Screening Demystified

At the checkpoint, remove your pet from the carrier just before you reach the bins. Carry the animal through the metal detector or let it walk on a short, non‑metallic leash while the carrier goes through the X‑ray machine. TSA officers may ask you to step aside for additional screening, so having a calm, well‑fitted harness ahead of time is crucial. For a full walk‑through of the procedure, consult the TSA’s official pet‑screening page.

Boarding and In‑Flight Rules

Southwest’s open‑seating system lets you board with your assigned group and choose a spot that best accommodates the carrier under the seat in front of you. Pets are prohibited from the first row, any emergency exit row, and seats equipped with inflatable seatbelts. Once seated, place the carrier under the seat and keep all zippers fully closed for taxi, takeoff, and landing. You may open the top flap briefly to comfort your pet mid‑flight, but the animal must never be removed from the carrier. Flight attendants will issue a single warning for violations; repeated failure to comply may result in being met by airport authorities upon landing.

Packing Essentials for a Pet‑Friendly Flight

Pre‑planning your carry‑on for your pet’s needs can prevent mid‑air stress. Stash these items in an easily accessible pouch:

  • Absorbent pee pads – line the carrier floor and carry two spares.
  • Collapsible silicone water bowl – offer water at the gate and during any layover.
  • Small bag of dry food or a few treats – only for long travel days; limit feeding to avoid motion sickness.
  • Leash and harness – a lightweight, non‑metallic harness helps during TSA screening.
  • Vaccination records and health certificate – keep them in a waterproof sleeve.
  • A familiar blanket or worn t‑shirt – your scent is a powerful calming cue.
  • Extra identification tags – attach one to the carrier and one to your pet’s collar.
  • Waste bags and a small towel – for inevitable accidents.

Pack these items thoughtfully, and you’ll be able to handle most situations without leaving your seat.

Tips for a Calm and Comfortable Flight

Success begins days before takeoff. Leave the carrier open in your living room so your pet can nap inside voluntarily. On travel morning, feed a light meal no later than 3–4 hours before departure and provide a short, brisk walk or an indoor play session to spend excess energy. At the airport, keep your pet inside the carrier except during security screening and at designated relief areas. Many terminals now offer dedicated pet comfort stations—check the airport’s website before you arrive so you know where to go.

Use your voice: a soft, steady tone during boarding and turbulence tells your pet that the environment is safe. Avoid the temptation to pass treats constantly; instead, offer one or two during takeoff to distract from the noise. If your pet vocalizes, resist the urge to pull it out—doing so only teaches that crying leads to freedom. Most animals settle once the engines reach a steady hum. Line the carrier with a blanket that smells like home, and if you’re flying to a colder destination, tuck a chemical‑free heat pad inside (check with the vet first).

What to Do If Your Flight Is Delayed or Canceled

Delays and cancellations affect pets just as much as people. If your flight is pushed back, check that the pet relief station is accessible from your gate without exiting the secure area. In cases of extreme delay or a gate change, a quick trip to the relief area can make a huge difference. Always re‑tag the carrier with your updated contact number if you receive a rebooked itinerary. Southwest’s phone agents can confirm whether the new flight still has room for your pet, but you may need to call quickly to secure a spot. During a lengthy tarmac hold, let a flight attendant know you have a pet onboard; they can advise on when it might be safe to offer water. Never open the carrier on an active taxiway.

Special Situations: Service Animals and Emotional Support Animals

Trained Service Dogs

Southwest welcomes service dogs that have been individually trained to perform tasks for a passenger with a disability. These animals travel free of charge and are not restricted by carrier size or weight. The airline requires the U.S. Department of Transportation Service Animal Air Transportation Form to be completed and submitted at least 48 hours before departure for flights to or from the U.S. mainland. The form attests to the dog’s training, health, and behavior. Onboard, the dog must be harnessed or leashed and remain under your control at all times. Unruly conduct—growling, urinating, biting—can cause the dog to be treated as a pet, triggering the standard pet fare and space restrictions.

Emotional Support Animals (ESAs) – Policy Update

As of early 2021, emotional support animals are classified as regular pets for travel purposes. They must travel in an approved carrier that fits under the seat, and the $125 pet fare applies. ESA registration cards or online certificates do not grant any special privileges. If a dog that has been providing emotional support is also trained to perform a specific task related to a psychiatric disability, it may qualify as a psychiatric service dog. In that scenario, you must complete the DOT form and meet all service animal standards. Otherwise, plan to book your ESA under the standard pet policy.

Traveling to Puerto Rico, Hawaii, and Interstate Considerations

Puerto Rico’s Additional Rules

Even though it is a domestic U.S. territory, Puerto Rico imposes its own entry requirements for dogs and cats. You must present a valid rabies certificate and a health certificate issued no more than 30 days before arrival. An import permit or an inspection by a Puerto Rico Department of Health veterinarian may also be required. Visit the USDA Animal and Plant Health Inspection Service site for the latest specifics. Southwest gate agents will verify your paperwork, and missing documents will result in denied boarding.

Hawaii’s Strict Quarantine Barrier

No pets are accepted in the cabin on any Southwest flight arriving in or departing from Hawaii—with the single exception of inter‑island flights entirely within the state. Hawaii requires all dogs and cats entering from the mainland to complete a rabies quarantine program that includes microchipping, rabies titer tests, and advance documentation. These steps cannot be satisfied for in‑cabin travel. If you need to relocate a pet to Hawaii, you must use an approved cargo service and follow the Hawaii Animal Quarantine guidelines exactly. Southwest does not offer pet cargo service.

International Itineraries Are Not an Option

Southwest operates exclusively domestic pet flights. If your trip involves a connection to an international destination, your pet cannot travel the entire route on a single airline. You’ll need to coordinate with the international carrier and meet the destination country’s import regulations, which often include microchip specifications, specific vaccines, and waiting periods after blood tests. Start that research months ahead.

Alternatives If Your Pet Cannot Fly Southwest

Professional Pet Sitters and Boarding

If your pet exceeds the carrier size, is not a cat or dog, or simply cannot handle the sensory overload of an airport, leaving them with a trusted professional is often the kindest decision. Book sitters and kennels well ahead of holidays. Tour the facility, discuss your pet’s routine, and leave detailed feeding and medication instructions. Many veterinary clinics offer boarding, which gives you the reassurance of immediate medical care if needed.

Licensed Pet Transport Services

For large dogs, brachycephalic breeds that may do better in climate‑controlled cargo holds, or animals that must relocate internationally, professional pet shipping companies can manage the entire process. They coordinate airline arrangements, provide the right travel crate, and handle import paperwork. Look for members of the International Pet and Animal Transportation Association (IPATA). While pricier than in‑cabin travel, a reputable shipper removes guesswork and ensures compliance with every regulation along the route.

Ground Transportation Solutions

For journeys under 500 miles or cross‑country relocations where air travel feels too risky, driving or using a pet‑friendly ground transport company offers full environmental control. Map out stops that include pet relief areas, book overnight accommodations that welcome animals, and keep the carrier secured on a seat with proper ventilation. Road trips eliminate airport chaos and let you set the pace entirely around your pet’s comfort.

Frequently Asked Questions

What types of pets are allowed on Southwest?

Only domestic cats and dogs may travel in the cabin. All other animals—birds, rodents, reptiles, insects—are prohibited, regardless of size or tameness.

What is the exact carrier size limit?

The maximum external dimensions are 18.5″ L × 8.5″ H × 13.5″ W. The carrier must fit entirely under the seat and remain stowed for the entire flight.

How much does it cost to bring a pet?

The standard pet fare is $125 each way on U.S. mainland flights and $35 each way on inter‑island Hawaii flights. Always confirm the latest pricing on Southwest’s official pet policy page.

Can I bring a pet on a flight to Hawaii?

Only inter‑island Hawaiian flights accept cabin pets. Any route connecting the U.S. mainland to Hawaii prohibits in‑cabin pets due to state quarantine regulations.

Are emotional support animals still recognized?

No. ESAs are now treated as standard pets and must travel in a carrier with the applicable fee. Only trained service dogs meeting DOT requirements may fly in the cabin without a carrier and free of charge.

How many pets can be on one flight?

Southwest allows a maximum of six pet carriers per flight. This cap makes advance phone reservations essential.

Where can my pet relieve itself at the airport?

Many airports offer pet relief areas. Locate them before you travel using the airport’s website or app. Inside the terminal, use a disposable pee pad in a family restroom if emergency strikes.

Is it safe to sedate my pet for the flight?

Most veterinarians advise against sedation because of the unpredictable respiratory effects at altitude. Focus on behavior training and natural calming aids under veterinary guidance instead.

What if my flight gets canceled with a pet?

Contact Southwest immediately to rebook and confirm pet space on the new flight. Keep your pet’s supplies accessible, and use the delay to visit a relief station.

Pre‑Flight Checklist

Run through this list before you leave for the airport:

  • Pet reservation confirmed via phone and payment receipt saved.
  • Carrier meets 18.5″ × 8.5″ × 13.5″ rule; soft‑sided design preferred.
  • Health certificate issued within 10 days (or 30 days for Puerto Rico).
  • Current rabies vaccination tag affixed to pet’s collar.
  • Absorbent pad placed in carrier; spare pad packed.
  • Water bowl, small food portion, leash, harness, and waste bags bagged.
  • Carrier clearly labeled with your name, phone number, and pet’s name.
  • Zip‑tie securing zipper pulls.
  • Familiar blanket or shirt inside the carrier.
  • Arrival at airport at least 45 minutes before departure to allow full‑service check‑in.

With thorough preparation and a firm grasp of Southwest’s pet policy, both you and your companion can enjoy a steady, uneventful flight. The rules may appear numerous, but each safeguard exists to protect animals, passengers, and crew alike. Book early, pack thoughtfully, and let the adventure begin the moment you step onto the jet bridge.