US airlines will no longer be required to transport emotional support animals after passengers insisted on bringing on board their horses, pigs, peacocks and turkeys for psychological reasons.
Wednesday's rule change by the US Department of Transportation now says only dogs qualify as service animals.
The agency said unusual animals on flights had "eroded the public trust in legitimate service animals".
Airlines say the old policy had been abused and was dangerous.
The new rule defines service dogs as "individually trained to do work or perform tasks for the benefit of a person with a disability", and says other animals should be treated by airlines as pets that can be placed in the cargo hold for a fee.
Previously, the federal government had no law regarding emotional support animals, which effectively required airlines to accommodate them as service animals despite complaints from passengers. Unlike pets, they were allowed to travel for free under the law known as the Air Carrier Access Act.
The review process drew around 15,000 public comments to the transportation department, the agency said.
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Trade group Airlines for America estimates that the number of emotional support animals on commercial flights jumped from 481,000 in 2016 to 751,000 in 2017.
"The Department of Transportation's final rule will protect the travelling public and airline crewmembers from untrained animals in the cabin, as well as improve air travel accessibility for passengers with disabilities that travel with trained service dogs," Airlines for America President Nicholas E Calio said in a statement.
Unlike service animals, emotional support animals are not required to have been trained to perform a specific task. There have been several incidents of unruly animals causing injuries to passengers and flights crews. Some of those incidents have led to lawsuits.
The ruling specifically says that a dog's breed should not be a factor in an airline's requirement to accommodate the service animal. Delta Airlines currently has a policy in place that forbids "pitbull-type dogs" that may be forced to change under the new government policy.
The decision was quickly applauded by airline industries, which have been trying for years to change the rule, and airline employee unions.
"The days of Noah's Ark in the air are hopefully coming to an end," Association of Flight Attendants President Sara Nelson told USA Today on Wednesday.