Reviewed October 12, 2026 by Pet Commute.
Frontier and Allegiant offer in-cabin pet travel subject to their rules. Spirit is no longer an option under its announced shutdown. A low passenger fare does not establish whether your pet can travel or what the complete journey will cost. Check the operating airline, route and carrier before buying a ticket.
Spirit: the old pet policy is historical
Spirit announced an immediate wind-down on May 2, 2026, with all flights cancelled. The Spirit fees and carrier allowances formerly listed here should not be used to plan a new journey. If an old itinerary involved Spirit, review a replacement airline’s requirements from the beginning; pet eligibility does not transfer with the passenger’s travel plans.
Frontier: confirm species, route and carrier
Frontier lists dogs, cats and several small animal species for domestic cabin travel. It does not accept new pet bookings for international travel and does not check pets as baggage. Its published container limits distinguish hard-sided carriers, up to 18 × 14 × 8 inches, from soft-sided carriers, up to 18 × 14 × 11 inches. The animal must have adequate room and the container must fit under the seat.
Check the current directional pet charge in Frontier’s booking information rather than relying on the older $99 fee quoted here. Verify the actual pet reservation along with the ticket.
Allegiant: dogs and cats, with carrier-specific limits
Allegiant’s policy covers domestic dogs and cats in cabin. It currently lists a $50 charge per segment per carrier. Its maximum closed dimensions are 18 × 12 × 11 inches for a soft-sided carrier and 17 × 11 × 10.5 inches for a hard-sided carrier. Pets must fit comfortably; the former blanket 20-pound limit in this article is not stated on the current pet policy page.
Allegiant requires an agent to check the pet and carrier at least one hour before scheduled departure. That is a check-in requirement, not a suggested time to arrive at the curb. Confirm destination rules separately.
Compare the whole trip
Write down the passenger airfare, pet charge for each segment, baggage, airport driving and any carrier purchase. Then compare itineraries with the same pickup and delivery endpoints. A cheap ticket with an inconvenient airport or difficult handoff may change the total considerably.
For an arranged flight nanny journey, ask which airline and ticket arrangement are proposed and which costs are included. Pet Commute’s coordinator can review available options with you; submitting a quote request does not purchase a ticket or reserve pet space.
When the pet cannot use an under-seat carrier
Another airline does not automatically solve a size or handling issue. Share the pet’s age, breed, measurements, number of animals and preferred dates before selecting a service. Discuss a ground transport proposal when cabin travel does not fit the pet’s needs.
Use our complete quote checklist and flight nanny versus ground guide to compare the scope of the journey.
Sources and current requirements
- https://www.flyfrontier.com/travel/travel-info/family-pets/
- https://www.allegiantair.com/traveling-with-pets
- https://www.prnewswire.com/news-releases/spirit-airlines-begins-orderly-wind-down-of-operations-302760586.html
Confirm the applicable airline, destination and trip requirements before booking. Your individual quote and booking documents describe your confirmed arrangement.
