Updated

United Airlines passengers better check the rules before heading to the airport with Fluffy and Fido, as the carrier has officially banned 21 breeds of dogs and four breeds of cats from flying in their cargo hold, including Shih-Tzus, Pit Bulls, bulldogs, and Burmese and Persian cats, among others.

The Chicago-headquartered carrier announced revisions to their PetSafe travel program, effectively banning ‒ as of June 18 ‒ short-nosed and snub-nosed dogs, as well as “strong-jawed” breeds from the transportation program “out of concern for higher adverse health risks.”

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Shih Tzu’s, Pit Bulls, Mastiffs, and French bulldogs are among the breeds now banned from United flights. (iStock)

In addition, cats and dogs are now the only animals allowed in the PetSafe program, a move that United spokesman Charles Hobart said was initiated to “further minimize risk and ensure the comfort of pets we fly.”

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The carrier is tightening the leash on its pet air transportation program. (iStock)

“Prior to today, we flew all sorts of animals. Geese, foxes, leopards, you name it, we pretty much flew it,” Hobart told People of the update. “We’ll only fly dogs and cats as pets that belong to our customers.”

“We understand that [this policy] can present challenges to folks who have traditionally flown their pets where they need to be, but our overwhelming concern is ensuring the comfort of those animals and this is how we have to do it,” Hobart added.

Between May 1 and Sept. 30, PetSafe pet air transportation will also not be available for flights through Phoenix Sky Harbor International Airport, McCarran International Airport, Palm Springs International Airport and Tucson International Airport due to "high temperature restrictions," a news release details.

Hobart said the update reflects United’s impetus to protect “the safety and comfort” of animals that fly with the carrier, explaining that the breeds banned were recommended by the American Humane Society. The organizations have teamed up “to improve the well-being of all pets that travel on United,” he said.

“As we continue our review process to ensure that we are always doing what's right, we are committed to making significant improvements in our program and adhering to the best practices of animal comfort, well-being and travel on behalf of our customers and their pets," Jan Krems, United's vice president of cargo, said of the partnership, announced May 1.

United did not elaborate on whether the airline planned to offer further alternatives to passengers flying with the banned breeds. The company's website still states that passengers can bring pets aboard the plane if they "remain in a kennel" and "in the floor space" below the seat.

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The policy changes come just over a month after the widely reported death in March of a French bulldog that suffocated in an overhead bin, after being erroneously placed there by a flight attendant for the duration of a trip from Houston to New York. United has since apologized and accepted full responsibility for the incident.

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As various carriers tighten the leash on policies for flying with pets, new legislation introduced in the U.S. Senate in late April aims to crack down on air travelers abusing current policies for traveling with emotional support animals rules and even establish a criminal penalty.