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Delta Air Lines is tightening the leash on service and emotional support animals, requiring human passengers to hand over more information about their pets before everyone gets cozy in coach.

Reports of animals urinating and defecating or biting have spiked some 84 percent in the last few years, forcing Delta to get tougher on some of the roughly 250,000 service or support animals that travel on its planes every year, the airline said Friday.

The solution: extreme vetting.

“Customers have attempted to fly with comfort turkeys, gliding possums known as sugar gliders, snakes, spiders and more,” Delta said in the statement. “Ignoring the true intent of existing rules governing the transport of service and support animals can be a disservice to customers who have real and documented needs.”

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Delta, the second-largest U.S. airline by passenger traffic, will require passengers hoping to fly with animals to provide proof of their pet’s training and vaccinations 48 hours before they board. The owners of emotional support animals will need to offer a document, signed by a doctor or licensed mental health professional, verifying that their animal can behave.

Last year, “Delta employees reported increased acts of aggression (barking, growling, lunging and biting) from service and support animals, behavior not typically seen in these animals when properly trained and working,” the airline said.

Among the recent incidents: A man was reportedly mauled by another passenger’s 70-pound emotional support dog as a Delta flight was boarding in Atlanta last June. The man could not escape because he was in a window seat and the attack left him with facial wounds requiring 28 stitches, according to The Atlanta Journal-Constitution.

Federal law permits service animals to fly in-cab with their owners — as long as they do not pose a threat to the health and safety of others.

Related: Where are there so many animals in the sky?

“The rise in serious incidents involving animals in flight leads us to believe that the lack of regulation in both health and training screening for these animals is creating unsafe conditions across U.S. air travel,” John Laughter, Delta's senior vice president of corporate safety, security and compliance, said in the statement.

The new requirements take effect March 1, the airline said.

American Airlines appeared to commend the new Delta rules, saying it was also looking into "additional requirements."

"Unfortunately, untrained animals can lead to safety issues for our team, our passengers and working dogs onboard our aircraft," the airline said in a statement. "We agree with Delta’s efforts and will continue to support the rights of customers, from veterans to people with disabilities, with legitimate needs.”