Sen. John Kennedy of Louisiana is adding his voice to the national outcry over a puppy who died after a United Airlines flight attendant forced its owners to stow their beloved pet in an overhead bin for a three-hour flight

Sen. John Kennedy of Louisiana is adding his voice to the national outcry over a puppy who died after a United Airlines flight attendant forced its owners to stow their beloved pet in an overhead bin for a three-hour flight.

Kennedy announced on Twitter Wednesday that he had written a letter to the president of United Airlines calling for an “immediate explanation” for the number of animals who have died recently in the airlines’ care.

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In his letter to United president J. Scott Kirby, the Republican senator cited U.S. Department of Transportation data stating that “18 of the 24 animals who died in major U.S. airlines’ care last year were in the care of United.”

“Another 13 animals in United’s care suffered injuries last year. For comparison, Delta and American each reported two animal deaths,” Kennedy added.

Image zoom John Kennedy DON EMMERT/AFP/Getty

“This pattern of animal deaths and injuries is simply inexcusable,” he wrote. “For many people, pets are members of the family. They should not be treated like insignificant cargo. Frankly, they shouldn’t be placed in the cargo hold much less an overhead bin.”

The family whose 10-month-old French bulldog, Kokito, was killed in the latest incident spoke out on Good Morning America on Wednesday.

“He was a member of our family,” Sophia Ceballos, 11, tearfully said in the interview. “He was like my brother to me.”

Ceballos, along with her mother, Catalina Robledo, and brother, 2 months, were traveling from Houston, Texas, back to their home in New York and decided to bring their pup along for the trip.

The return flight ended in tragedy after the flight attendant made them stow the dog in the overhead bin.

Image zoom Gary Hershorn/Getty

“We were gonna put him under the seat and then the flight attendants came, she said, ‘You have to put him up there because it’s going to block the path.’ And we’re like, ‘It’s a dog, it’s a dog.’ And she’s like, ‘It doesn’t matter you still have to put it up there,’ ” Ceballos recalled on GMA. “She helped her put it up, and she just closed it like it was a bag.”

Fellow passenger Maggie Gremminger told PEOPLE that she was “stunned” to see the puppy being stowed in an overhead bin but understood why the family followed the flight attendant’s instruction.