Delta Air Lines said it will ban service and support animals under four months old, and will also ban emotional support animals on flights longer than eight hours.
The change, effective Dec. 18, is the latest tightening of policies on service animals and emotional support animals by Atlanta-based Delta.
The airline said it has seen an 84 percent increase in incidents reported involving service and support animals in 2016 and 2017, "including urination/defecation, biting" and a mauling by a 70-pound dog.
Delta said its new policy aligns with the CDC vaccination policy, and the limit on emotional support animals on long flights “is consistent with the principles outlined in the U.S. Department of Transportation’s Air Carrier Access Act.
“These updates support Delta’s commitment to safety and also protect the rights of customers with documented needs - such as veterans with disabilities - to travel with trained service and support animals,” said Delta senior vice president of corporate safety, security and compliance John Laughter in a written statement.
Some of the the airline's previous policy changes have prompted criticism from groups representing people who use service animals.
The new policy takes effect for tickets booked Dec. 18 or later. Regardless of booking date, it will also take effect for flights Feb. 1 or later. Delta said it will contact customers to adjust reservations if the policy affects them.