Alejandro was found dead in his crate in the cargo facility at Detroit Metropolitan Airport near Detroit, Michigan, Fox News reported.

Michael Dellegrazie, the owner, said the dog was alive when the flight from Phoenix, Arizona, landed at the airport around 6.30am local time on Wednesday for a scheduled stop.

About two hours later, Alejandro was found dead by an agent, who said the dog was unresponsive. He had reportedly vomitted in his crate. The dog’s blanket also had blood stains.

The tragedy comes months after a french bulldog died in a plane’s overhead compartment on a United Airlines flight.

Mr Dellegrazie said Alejandro was like a “family member”.

“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,” Mr Dellegrazie told WDIV-TV.

Mr Dellegrazie, who owns the dog with his girlfriend, said he’s grasping to understand how his Pomeranian had died while heading to Newark, New Jersey.

“Things need to change, and I’m here to tell you that the people will make them change,” Evan Oshan, Mr Dellegrazie’s lawyer, told the news site.

A Delta Air Lines spokesman told Fox News the dog was seen in good health after the flight and brought to the staging area.

The kennel facility determined the dog had died about two hours later and airline officials immediately notified the owner. The spokesman added Delta offered to conduct a necropsy, but was told by the owner to hold off.

In a statement, Delta said it was conducting an investigation.

“Pets are an important member of the family and we are focused on the wellbeing of all animals we transport,” the statement read.

“Delta 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.

“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,” it added.

It’s still unclear what caused the dog’s death. Mr Oshan said the family was “devastated” over the incident.

Oshan is the same lawyer who represented the owners of the french bulldog that died on a United Airlines flight. The 9-month-old puppy, Kokito, died after he stopped breathing on a flight from Houston to New York in March. A flight attendant told the owner to put him in the overhead bin rather than under the seat.

The french bulldog that died in March was not part of the cargo program.

The Associated Press contributed to this report.

This article originally appeared on Fox News and was reproduced with permission.