WASHINGTON — With hundreds of thousands of emotional support animals taking to the skies on U.S. airlines, Congress may start pulling a tighter leash.Two new legislative options emerged this week to address a hairy issue for American Airlines, Southwest Airlines and other carriers, which are dealing with a growing number of injuries, confrontations and other problems resulting from comfort pets.A bill by Sen. Richard Burr, R-N.C., would tighten rules so only "service animals," as defined by the Americans with Disabilities Act (ADA), could fly uncaged in the cabin. An amendment by Rep. Bill Shuster, R-Pa., would instead direct the U.S. Transportation Department to clarify existing rules.Either option would be contentious, despite wide agreement that the current setup is too open-ended and subject to bald-faced abuse.But Burr’s approach, which is backed by the airline industry, is sure to generate a roar. His legislation would effectively prevent emotional support animals from getting on board, putting him at odds with mental health advocates who see the pets as vital for some fliers.The senator, however, cast his bill as common sense."One doesn’t have to look far to find rampant cases of abuse where even emotional support kangaroos have been allowed to fly on planes to the detriment of fellow travelers and handlers of trained service animals," he said in a news release.No one disputes the growing rise of emotional support animals.U.S. airlines flew 751,000 comfort pets last year, an 80 percent jump from the previous year, according to an informal survey by industry group Airlines for America. Those animals include dogs and cats, yes. But also rabbits, ducks, parakeets and monkeys.No one disputes the potential pitfalls of a flying zoo.Association of Professional Flight Attendants president Nena Martin, who represents American Airlines flight attendants, wrote that the status quo has "led to a variety of issues inflight that are not readily solvable in a small, contained cabin at 35,000 feet where resources are limited."And no one disputes the underlying problem.While the ADA has strict rules for how service dogs used by those with disabilities can function in public spaces, another law known as the Air Carrier Access Act of 1986 is much more generous in what kind of animals can come in an airplane cabin.The intractable question, however, has been what to do about it all.Most of the policy attention has focused on shoring up the looser aviation rules, which accommodate any animal that is "able to provide assistance to a person with a disability" or that "assists persons with disabilities by providing emotional support."