U.S. commercial airlines have reported 29 animals died and 26 were injured traveling in the cargo hold of airplanes in 2012.
Airlines, such as American Airlines, have safety policy for the pets. AA asks for health certificates from the pet owners and it checks the comfort of the kennel before the flight.
Kendra Hays' Great Dane Tucker had a clean bill of health from the vet and a custom-made kennel. But the dog had suffered a heat stroke when the plane touched down in Seattle. He was covered in blood and saliva.
Other dogs have suffered similar situations. A pit bull mauled himself on a flight from Charlotte to Atlanta. Another dog was killed when he escaped onto the runway.
The Humane Society investigators say many animals are injured by self-inflicted wounds and panic attacks due to hours of stress.
The U.S. Transportation Department is proposing stricter rules requiring airlines to produce more detailed reports of the safety of pets on their planes.