The airline is adding two more restrictions. Effective Dec. 18, your service or support puppy or kitten might not be allowed to fly with you. Any animal under four months will be banned on any Delta flights “due to USDA vaccination requirements,” according to the airline.

Passengers will also not be able to fly with their emotional support animal on any flight that is longer than eight hours. This policy is effective December 18 as well, but for those who have already purchased a ticket and put in a request to bring their animal, an exception will be made through February 1.

In March, Delta began requiring passengers to provide additional documentation proving their need for an emotional support animal. In June, the airline announced it would begin limiting passengers to one animal, and would be banning “pit bull type dogs” entirely.