Heat might have killed seven puppies that died in the cargo hold of an American Airlines jet this month.
Spokeswoman for Fort Worth-based American Airlines Mary Frances Fagan said Tuesday that necropsies on the puppies were inconclusive but found that heat "may have been a factor."
Fagan said the flight complied with company policy that prohibits shipping animals when outside ground temperatures exceed 85 degrees.
The National Weather Service recorded 86 degrees in Tulsa while the plane, which was delayed from taking off for an hour, was still on the ground at 8 a.m. But American relies on temperatures reported by The Weather Channel's website, and Fagan said those readings "at loading, pushback, take-off and arrival" were within the 85-degree limit.
Fagan also said the puppies that died might have had other health problems because 17 other dogs survived the same flight.
American declined to release the necropsy reports on the dead puppies. The airline said it carries more than 100,000 dogs a year.
The puppy deaths outraged animal-rights groups. The Humane Society of the United States and the Animal Legal Defense Fund called on government officials to investigate whether the airline violated federal rules on shipping animals. In 1994, the U.S. Agriculture Department fined Delta Air Lines $140,000 after 32 puppies suffocated in the cargo hold of a jetliner that was delayed for two hours.
The American Society for the Prevention of Cruelty to Animals recommends that owners avoid shipping pets in the cargo hold. Most airlines will only allow pets in the passenger cabin if they are small enough to fit in a carrier under a seat.