Delta Airlines announced Monday it would ban puppies from serving as service or emotional support animals on its flights.

Delta Airlines said Monday it would prohibit emotional support animals in cabins for flights longer than eight hours and ban all service animals and emotional support animals under four months old on all airplane routes beginning December 18, the Atlanta Journal-Constitution reported.

The airline said it would make exceptions for passengers who already bought a ticket and requested an emotional support animal until February 1.

Delta said the uptick in reported incidents in which service and support animals have urinated, defecated, or bitten someone while in flight went up by 84 percent led to the policy change.

“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.

The airline said it would reach out to affected customers to help them change their reservations if the change in policy disrupts their travel plans.

Other airlines are cracking down on policies regarding emotional support animals.

Southwest Airlines announced in August that emotional support animals are limited to dogs and cats, and all animals must be accompanied with a doctor’s note.