Revealed: What killed dog left in plane's overhead compartment

The French bulldog who was stored in an overhead locker on a United Airlines plane died of suffocation, an autopsy has revealed.

The 10-month-old puppy was found dead after a three-and-a-half-hour flight from Houston to Chicago in March.

The family claimed they were told by the cabin crew to place the carrier in the overhead compartment, despite their protests that the dog, named Kokito, was inside.

Kokito the French bulldog died after being stored in an overhead compartment. He was stored in his carry case, pictured right. Source: Supplied

They said they heard Kokito barking during the flight, but were not allowed to stand up and check on him as there was turbulence.

On landing they found the little dog had died.

Kokito’s necropsy, which was conducted at Cornell University, found the pup was subjected to decreased levels of oxygen.

Stress combined with the French bulldog’s narrow airway were also factors, according to TMZ.

The United Airlines flight travelled from Houston to Chicago. Source: Getty/File

On Tuesday, United Airlines resumed the shipment of pets in its airplane cargo holds after having paused the program for improvements following Kokito’s death.

United said it is partnering with the American Humane animal rights organization to improve the well-being of the pets it flies

Short- or snub-nosed cat and dog breeds, like French bulldogs, and strong-jawed dog breeds, like Mastiffs, will no longer be permitted to fly as cargo

According to the U.S. Department of Transportation, of the 24 animals that died on U.S. carriers last year, 18 were on United flights.