RabbitsDudu Greenspan/Flash 90

A 3-foot-tall continental giant rabbit named Simon died while traveling on a United Airlines Flight from London's Heathrow Airport to Chicago O'Hare.

Simon, 10 months old, was on his way to his new owner, who Worcestershire rabbit breeder Annette Edwards said is "famous."

Speaking to The Sun, Edwards said, "Simon had a vet’s check-up three hours before the flight and was fit as a fiddle. Something very strange has happened and I want to know what. I’ve sent rabbits all around the world and nothing like this has happened before. The client who bought Simon is very famous. He’s upset."

She also said her US customer is considering filing a lawsuit against the airline.

Simon's father Darius grew to be the world's largest rabbit, at 4 feet 4 inches tall (1.32 meters). Simon himself was expected to grow to be the world's second-largest rabbit.

A United Airlines spokesperson said the airline had offered assistance to one of its customers and was reviewing the incident.

"We were saddened to hear this news," the spokesman said. "The safety and well-being of all the animals that travel with us is of the utmost importance to United Airlines and our PetSafe team."

"We have been in contact with our customer and have offered assistance. We are reviewing this matter."

According to the US Department of Transportation, 35 animal deaths have occurred on 17 carriers in the US 2015. 14 of those animal deaths occurred on United Airlines.

In addition, nine animals out of the nearly 100,000 were injured on United Airlines flights during the same period.