Delta Air Lines has given a few of its passengers something to cry about: new rules that tighten the leash on “emotional support” animals, or ESAs.

The new guidelines, announced on January 19, will require travelers with an ESA to submit a signed veterinary health form or immunization record, an “emotional support” animal request form signed by a doctor or mental health professional, and a signed confirmation of animal training form.

Passengers wishing to travel with an ESA will need to submit these materials to Delta’s new Service Animal Support Desk at least 48 hours prior to travel.

Delta’s announcement comes on the heels of increased abuse of lax airline regulations of “emotional support” animals. Delta said its airlines carry nearly 250,000 service or support animals every year — many of which are for passengers with no apparent physical disability.

“Customers have attempted to fly with comfort turkeys, gliding possums known as sugar gliders, snakes, spiders and more,” Delta wrote.

In one highly-reported incident, passenger Marlin Jackson was mauled by another passenger’s “emotional support” Labrador mix aboard a June flight from Atlanta to San Diego. Trying to get to his window seat, Jackson squeezed by the passenger and his dog, who were in the middle seat. The dog lunged at Jackson’s face and attacked him for about 30 seconds. Jackson needed 28 stitches.

Delta also reported an 84% percent increase in “reported animal incidents” since 2016, including urination and defecation.

“In 2017, 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,” Delta wrote.

An “emotional support” animal is said to ease an owner’s anxiety and other emotional problems. Unlike service animals or psychiatric support animals, they are not trained to perform any tasks related to their owner's physical or mental disabilities.

The 1986 Air Carrier Access Act gave travelers wide latitude to travel with a variety of animals, and while airlines are allowed to require documentation, many don’t. Some passengers, as ABC News illustrated in an amusing investigation, bring bogus “certificates” in case the airline requests medical documentation verifying the need of an ESA.

Some passengers have, of course, gamed the system that the 1986 law encouraged. That same law, though, does allow airlines to determine whether an ESA would “pose a direct threat to the health or safety of others” and “whether it would cause a significant disruption of cabin service.”

Delta said that ESAs have been “regularly reported to occupy seats, stretch across the aisles and move throughout the cabin during flight, often without restriction."