The airlines definitely have a dog in this fight.

For the past month, the airlines have been opposing a "pets on planes" provision that was tacked onto the Federal Aviation Administration reauthorization bill.

Along with multibillion-dollar issues such as modernization of the air transport system and how many flights there should be at Reagan National Airport, "pets on planes" focused on how to keep flying felines, canines, monkeys, rabbits, mice and other warm-blooded animals unharmed in transit. At least 500,000 animals are airborne annually.

Sen. Frank R. Lautenberg (D-N.J.) originally introduced the bill as the Safe Air Travel for Animals Act. It's now referred to as the "Boris Bill," after Boris the dog, about whom more later.

The legislation calls for increasing the liability of airlines for damage to pets to $2,500, doubling civil fines that can be imposed by the government to $5,000 per unfortunate pet incident, improving air flow and temperatures in the cargo holds of planes, and establishing a reporting system that would tell pet owners which airlines have the best--and worst--track records in handling Fido and Fluffy.

Air transport of animals is regulated by the Agriculture Department's Animal and Plant Health Inspection Service. Its inspectors check where animals are kept on the plane, temperature, ventilation, and whether they are monitored properly and given food and water. There are no requirements that the airlines report any problems or fatalities of animals to the government, so it's unknown how many mishaps actually occur.

"Additional regulation is unnecessary," said David Fuscus, spokesman for the Air Transport Association. "Airlines do an excellent job transporting pets and other live animals, and there already is a government agency that regulates this area. You can find an example of anything in a system this big."

Individual carriers such as US Airways and United Airlines said they make sure pets have a safe in-flight experience even though they may not always be riding first class, or even economy or even in the cabin. They said baggage handlers are trained how to load and unload animals, airlines figure out how many pets can be airborne depending on the amount of oxygen available in the cargo hold, temperatures are monitored, and animals get priority seating--they get loaded last and come off first.

"If you have injuries or deaths, USDA would be inundated with complaints. Our public is very vocal," said Carl Kole, United Airlines' administrator for special cargoes and chairman of the Air Transport Association's Live Animal Task Force.

Animal advocates make no bones about disagreeing.

They have widely circulated on Capitol Hill horror stories about animals coming off planes maimed or dead. They stress that some of the cargo holds do not have enough oxygen to support carrying animals; they say baggage is thrown on them and they may be exposed to extreme temperatures. Government inspections are too infrequent, they charge.

And then there is Boris, poster dog of airline mishaps.

His owner, Barbara Listenik, is still fighting with Delta Air Lines over her dog's treatment three years ago. She said Boris escaped from his crate after landing at La Guardia Airport, ran around the tarmac, raced through the terminal and ended up on the streets of New York, bloodied and sick.

"They showed me a bloody, empty cage. I went over to the cargo supervisor and he handed me a baggage-claim form," Listenik said. "I was devastated."

She said Delta reneged on paying Boris's $3,600 vet bill but refunded the fare and paid $1,000 toward the dog's expenses.

Delta said it did not have "details dating that far back" regarding Boris.

The pet provisions have sparked fierce lobbying by animal groups, which are divided on the issue.

The American Society for the Prevention of Cruelty to Animals, the Humane Society of the United States, the Doris Day Animal League and others want the full plate of provisions. "That there isn't an acknowledgment that animals are worth more than a damaged suitcase or a set of golf clubs is appalling," said Nancy Blaney, director of the national legislative office for the ASPCA. "Airlines can't be charged by USDA time and time again and say they don't have a problem."

Last year, US Airways and American Airlines settled several cases with the Agriculture Department. The government alleged in those cases that the carriers violated the Animal Welfare Act. Alleged violations ranged from a cat being crushed by cargo to a river otter being subjected to improper temperatures. Each airline agreed to contribute $25,000 to study safe handling of animals.

Cat fanciers, dog breeders, the Zoo and Aquarium Association, the pet industry, and the Congressional Sportsmen's Caucus said they fear the legislation could result in animals being taken off the manifest entirely.

The issue is still open because House and Senate conferees did not come to an agreement on the FAA bill. As far as the pet provisions go, the tentative agreement now among conferees is to recommend more training for airline personnel handling animals and to require airlines to report to the Department of Transportation on a monthly basis any losses, injuries or deaths of animals.

Despite their success in eliminating most of the provisions of the Lautenberg bill, the airlines say there should be a hearing on the issue. Lautenberg's spokesman said as long as the bill remains unfinished, the pets-on-planes provision is alive.

And, Rep. Peter A. DeFazio (D-Ore)., a conferee on the FAA bill who has three large dogs and two cats, unleashed a fusillade of criticism against the airlines for resisting the measure.

"Knowing what I know now, I'd never ship one of my dogs until we get a better handle on the situation," DeFazio said.