LONDON >> United Airlines is reviewing its handling of a giant showcase rabbit that died after being shipped across the Atlantic from Britain on one of its flights, the latest in a growing list of customer complaints.

Distraught breeder Annette Edwards told The Associated Press by phone today that a veterinarian had checked Simon — a 10-month-old, 3-foot-long continental rabbit — shortly before the animal was placed on a United flight from London’s Heathrow Airport to Chicago’s O’Hare.

Edwards said Simon is the offspring of Darius, which the Guinness World Records lists as the world’s longest rabbit at 4 feet 3 inches.

“Simon had his vet check just before getting on the plane,” she said from Worcestershire in central England. “He was fit as a fiddle.”

United spokesman Charles Hobart said the rabbit was moving around in its crate and appeared healthy when taken off the plane in O’Hare, waiting to be put on another flight to Kansas City. About a half-hour later, at the company-run pet facility, Simon seemed to be sleeping. Shortly after that, a pet facility employee opened the cage and found the rabbit dead. He says the airline is reviewing its handling of the animal.

“We won’t know the cause of death, because we offered to perform a necropsy free of charge — that’s standard procedure — but the customer didn’t want us to perform a necropsy, and we understand,” he said.

Hobart said the airline offered compensation to the breeder but would not disclose the amount.

Bryan Bergdale, a farmland investment manager, said he bought the rabbit for his boss, who had hoped to show it at the Iowa State Fair. He had driven from the Des Moines area to Kansas City and was nearing the airport last Thursday when United called with the bad news. At first, he didn’t believe it.

“We’d built a pen and had toys all ready. It’s sort of a sad deal,” he said.

Bergdale, 29, said he’d tracked down the breeder and bought the rabbit for his boss, Steve Bruere, who owns a farm real estate company in the Des Moines suburb of Clive. Bergdale said the rabbit cost $530 and the shipping was $1,800.

Bergdale said the United representative didn’t say anything about compensating him for the loss.

“We’re still in the mourning process,” he said. “We’re not quite sure what we’re going to do.”

United had the second-highest level of animal deaths and injuries of any U.S. airline last year, or 2.11 per 10,000 animals transported, according to the U.S. Department of Transportation. Only Hawaiian Airlines was worse at 3.99, the result of three deaths among the 7,518 animals it transported.

United transported 109,149 animals last year, second only to Alaska Airlines with 112,281. United reported nine deaths and 14 injuries, the highest figures for each category among U.S. carriers. Alaska reported two deaths and one injury.

United said it works to protect the safety of animals through its PetSafe program, which is staffed 24 hours a day and allows pet owners to track their animals from point of origin to destination.

“Travel can be stressful for animals,” Hobart said, adding that the carrier has plenty of tips for those who do decide to ship their animals.

United is already working to repair its battered image after a passenger who refused to give up his seat on an overbooked flight was forcibly dragged from a plane at O’Hare Airport.

Airport security officers removed David Dao, a 69-year-old from Kentucky, from the United Express flight. Images of his bloodied face were widely circulated on social media, forcing United CEO Oscar Munoz to apologize. Munoz was widely faulted for his early responses to the situation. He first blamed Dao but later apologized repeatedly for United’s handling of the situation.

Two weeks earlier, United was criticized after a gate agent stopped two young girls from boarding a flight because they were wearing leggings. The airline said leggings violate the dress code of the United Pass program, a benefit for employees and their dependents.

The airline said last week that Munoz would not automatically become chairman of the carrier’s parent company, United Continental Holdings, next year as originally planned.