An 8-year-old dog was found dead during a layover near Detroit, on Wednesday, his owners and the airline said. The plane carrying the Pomeranian called Alejandro was en route from Phoenix to Newark, New Jersey.

Michael Dellegrazie, the owner, said the dog was alive when the flight from Phoenix landed at the airport for a scheduled layover. About two hours later, the dog was found unresponsive by an agent in his crate. The dog’s blanket had blood stains and it had vomited in the crate, reports said.

"We lost a family member. That's exactly what happened, and somebody has to be responsible for it. He was in their care and they didn't take care of him,” Dellegrazie told NBC-affiliated television station WDIV-TV.

Dellegrazie's attorney, Evan Oshan said: "The family is very upset... This is essentially their family member who died. To say they are upset is a gross understatement."

In a statement, Delta Air Lines said it is "conducting a thorough review of the situation to ensure this does not happen again and have been working directly with Alejandro's family to support them however we can."

It added, "As part of that review, Delta offered to have Alejandro evaluated by a veterinarian while in our possession to find out more about why this may have occurred. We are disappointed that we were not allowed to have a necropsy performed immediately following this unfortunate situation. The family now has Alejandro and we continue to offer our support."

This is not the first death of a dog while in the care of U.S. airlines this year.

In February, a bulldog died of unknown causes on Hawaiian Airlines. In March, a German Shepherd died of natural causes on a Delta flight and a French bulldog dog died after it was forced into the overhead bin of a United Airlines flight.

In May, United said it would no longer accept 21 breeds of dogs and four breeds of cats due to high risk of respiratory issues.

At the time, United also said that it will be working with the American Humane organization on pet handling policies and practices.

“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,” said Jan Krems, United’s vice president of cargo.

According to Department of Transportation data, of the 506,994 pets transported by U.S. airlines in 2017, 24 died, 15 were injured and one was lost.

Delta Air Lines
A Delta Air Lines plane arrives in Salt Lake City, Jan. 12, 2018. Reuters/Mike Blake