Better buckle up, Fido — Delta Air Lines has announced that emotional support animals will no longer be allowed on flights longer than eight hours.

The rules for pups are getting tighter too, since neither support animals nor trained service animals will be allowed on any Delta flights if they are under four months old, regardless of flight length.

Both changes are slated to take effect on Dec. 18, the Atlanta-based carrier confirmed in a press release published on Dec. 10.

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“We will continue to review and enhance our policies and procedures as health and safety are core values at Delta,” John Laughter, Senior Vice President of Corporate Safety, Security and Compliance said in the announcement. “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.”

According to the notice, the airline says exceptions will be made until Feb. 1 for customers who have already purchased a ticket and asked to bring a support animal. In addition, service and support animals under four months old will not be allowed onto any flight on or after Feb. 1.

As noted in the press release, Delta’s decision comes in the wake of an 84 percent spike in reported incidents involving service and support animals through the 2016-2017 period, including urination, defecation, biting and an attack by a 70-pound dog (which occurred aboard a Delta flight), the Atlanta Journal-Constitution reports.

“The updated support and service animal age requirement aligns with the vaccination policy of the CDC, and the eight-hour flight limit for emotional support animals is consistent with the principles outlined in the U.S. Department of Transportation’s Air Carrier Access Act,” the release states.

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The subject of emotional support and service animals on airplanes has proven to be one of the most controversial travel topics of the year, ever since an emotional support peacock named Dexter and his owner were rejected from boarding a United Airlines flight in January. A few months later, a French bulldog died midflight after being accidentally placed into an overhead bin by a United Airlines flight attendant for the duration of the trip.

Various carriers have been tightening the leash on their respective rules regarding the transportation of both companion and service animals in the high skies.

The Associated Press contributed to this report.