Michael Jarboe of Miami paid extra for special airline dog handlers to ensure the safety of his 2-year-old mastiff, BamBam, on a cross-country flight.
Instead, following a layover in Houston in 32-degree heat, baggage handlers found BamBam dead on arrival in San Francisco.
Just in time for the holiday travel season, a Change.org petition is calling for new federal rules holding airlines responsible for deaths of animals like BamBam.
More than 100,000 signatures were logged on Jarboe's petition, more than half of them added in the past two weeks.
Jarboe said one of his goals is to make pet owners aware about the danger of airline travel.
BamBam, who died in 2012, is hardly alone.
Pets flying with their owners are killed, injured or lost on average once every 10 days, according to Mary Beth Melchior, founder of the watchdog group Where Is Jack Inc. who keeps a tally of large carriers' reports to the US Department of Transportation.
Her organisation is named for a 5-year-old cat who died in 2011 after being lost for two months in New York's John F. Kennedy International Airport.
"You run the same risk of losing your pet as you do your luggage," said Jarboe. "It's Russian roulette."
The Humane Society of the United States suggests driving with your pet or leaving your animal at home with a pet sitter before choosing airline travel.
"Air travel can be so quick that you may think a plane is the best way to transport your pet. Think again. Air travel isn't safe for pets. The HSUS recommends that you do not transport your pet by air unless absolutely necessary," the organization's website cautions.
The tragedy of BamBam gained steam at Change.org after the petition was linked to Janet Sinclair's Facebook page titled "United Airlines Almost Killed My Greyhound" dedicated to her dog Sedona's flight experience in July.
Sinclair and Jarboe said they both chose to fly with their dogs on United because of its highly regarded Pet Safe program, which was started at Continental Airlines before the carriers' merger.
Both said the program promised their dogs would be held before and after flights and during layovers in an air-conditioned cargo facility, and transported to and from the planes in an air-conditioned van.
They say the system broke down during layovers in Houston where they say the dogs were left on the tarmac and in non air-conditioned cargo spaces in the summer heat for hours between flights.
"Our goal is the safe and comfortable travel of all the pets that fly with us," United's Megan McCarthy said on Tuesday in an emailed response to Reuters concerning the cases.
"On the rare occasion we don't deliver on that goal, we work with our customers, their vets and our team of vets to resolve the issue," she added.
Jarboe said he and his partner could see BamBam from their seats on the plane arriving for the second leg of the flight on a luggage cart with baggage handlers, instead of the promised air-conditioned van and special dog handlers.
"We could see right in the kennel. He was standing there swaying there back and forth with his tongue hanging out farther than I've ever seen it, drooling," Jarboe said.
Sinclair said she watched as baggage handlers in Houston "kick Sedona's crate, kick, kick, kick it six times to get it under the wing and left it there to boil on the tarmac."
Jarboe said United reported that its autopsy of BamBam was inconclusive after the death, but that his own vet was convinced the dog died of heatstroke. Jarboe said United eventually paid him about US$3,770 (NZ$4636), the price of a new dog and crate.
Sinclair said United agreed to pay Sedona's hospital bill of about US$2,700 (NZ$3320) for treatment of what the vet diagnosed as heat-stroke and dehydration. But Sinclair said she declined the offer because of an airline condition that she sign a confidentiality agreement.
For holiday travellers thinking about flying with a pet, Jarboe, Sinclair and Melchior offer the same advice: Don't.