A spokesperson for Daniel K. Inouye International Airport told KGW8 that the airport would not have denied the family's request under the circumstances.

While waiting for the flight, the Engelgaus said they asked the crew at the gate if they could take their dogs out of the transport box, but they refused.

They were allegedly told they had to keep their dogs in the crates even though they were showing signs of overheating, so when they took them to the pet toilet area, they let them out of the crates for a while so they could cool down.

“We kept them in the shade and gave them water to cool them down,” Gary said. “We gave them water. We were out there for about 40 minutes.”

After boarding the plane, Gary said the dogs seemed to be getting too hot again, so they unzipped the carrier and waved the safety card in front of them.

They then asked a flight attendant if they could take the dogs with them, but were denied permission. This is likely because Alaska Airlines policy states that dogs must remain in their crates in the boarding area and during taxiing, takeoff, and landing.

The couple asked for ice for the dogs instead, but by the time they arrived, Frank had already stopped breathing.

“I pulled him out of the carrier and his eyes were open. His tongue was hanging out a little bit and he wasn't moving or breathing,” Gary said.

Angie claimed that it was obvious that the dogs were in distress because of the heat, but they were not allowed to take the dogs out.

French Bulldogs are a brachycephalic breed and are prone to suffering from brachycephalic obstructive airway syndrome (BOAS). Due to their shortened muzzle, nose, and other genetic factors, French Bulldogs are prone to oxygen deprivation, which leads to snoring and other more serious problems.

For the remaining five and a half hours of the flight, the couple held their other two dogs in their arms.

Following the event, Angie said they wanted to see a change in policy that was more dog-friendly.

Alaska Airlines said it was saddened by the reported loss of Frank and was aware of the incident.

“Our crew members followed their procedures regarding pets on board aircraft and provided special care for guests throughout the flight,” they said in a statement to KGW.

Read more: Travelling with a dog? Here are some good tips

From January 2015 to December 2020, Alaska Airlines transported more animals than any other U.S. airline (730,000) and had an average incident rate of 0.26 per 10,000 pets transported.

New Zealand passengers can take their pets on board, but only with certain airlines.

Air New Zealand allows pets in the cargo hold. Only certified service dogs are allowed to fly in the cabin. From May 2024, there will be a flat fee of $120 for pets to be carried domestically.

Jetstar does not allow pets except for certified service dogs.