The Humane Society Recommends Not Transporting Pets by Air Unless Absolutely Necessary

More pets died on Delta flights last year than on any other airline, a government report reveals. But a closer look at the records shows that the pets' owners may have been as much to blame as the airline.

The report, issued each year by the U.S. Department of Transportation, shows that 19 of the 35 air-travel-related pet deaths in 2011 took place in the baggage holds of Delta planes, up from 16 in 2010. Five pets were also injured on Delta last year, more than on any other airline.

"The loss of any pet is unacceptable to us," Delta spokesman Anthony Black told the Atlanta Journal Constitution. "We are working to improve the processes and procedures to ensure that every pet arrives safely at its destination." Delta pointed out that it transports more pets than many other airlines (some, like Southwest and AirTran, don't allow pets to travel in the cargo hold at all), and that less than 0.2 percent of pets that fly Delta have been injured or killed.

Delta representatives denied that the pets had been mishandled, and detailed accounts of each incident seem to confirm that. Several of the pets had medical problems that were disclosed during check-in; other pets were found to have congenital defects, and a few had to be euthanized after self-inflicted injuries in their carriers. Age may have been a factor in some of the deaths, such as those of 17-year-old and 14-year-old cats, and the length of the trips may also have been an issue (13 out of the 19 deaths were on overseas flights). One dog, a mini pincher, died without even making it onto the plane -- handlers refused to load him because he was having trouble breathing. Three of the victims were English or French bulldogs, which Delta usually refuses to transport because of the snub-nosed breeds' respiratory problems.

According to Delta's guidelines, the airline "does not accept animals which exhibit signs of injury, distress, or are demonstrating efforts to escape and that Delta reserves the right to refuse pets as checked baggage if the health of the animal is in question and/or if the animal's health may be jeopardized by the extreme conditions." But a few of the pets that died were over the allowable weight limit, had been sedated, or had recent and obvious injuries, yet had been accepted for transport anyway. Delta also does not allow pets checked as baggage from May 15 through September 15, in order to avoid exposing them to extreme heat in the cargo hold, but eight of the 19 deaths occurred during that time frame last year.

Delta is not the only airline having a problem transporting pets. Last year, five pets died on American Airlines, four on Alaska Airlines, three on continental, and two each on Hawaiian Airlines and United Airlines, according to the report. In 2010, seven out of 14 puppies died on an American Airlines flight from Tusla, Oklahoma, to Chicago after it was delayed in hot weather.

This week, United Airlines announced that, starting in March, the carrier and its subsidiaries will transport pets only as cargo rather than checked luggage. The third-party fees are astronomical, they admit, but spokeswoman Mary Ryan told ABC News that pets "will now have a dedicated staff and temperature-controlled vans instead of the inhospitable baggage compartment," which will "lead to a better experience for pets."

The Humane Society recommends not transporting pets by air unless absolutely necessary, and suggests bringing small pets with you into the passenger section whenever possible.

If you are planning to travel with pets, take them to the vet for a complete physical first (airlines may require health certificates in order to allow your pet on board, and other countries may have quarantine and vaccination requirements to meet upon arrival). Check with your airline to make sure your pet's carrier meets their standards, and take the time to familiarize your pet with the carrier before his or her first flight, suggests the experts at WebVet.com. Booking a direct flight will minimize the chances of a missed baggage connection and exposure to extreme temperatures.