Delta Air Lines will be tightening requirements for passengers traveling with onboard service and emotional support animals following an increased number of animal-related safety issues on flights over the last several years.

If you’re planning a flight longer than eight hours, Delta Air Lines says you can’t bring an emotional-support animal with you.

The rules for pups are getting tighter too. Neither support animals nor trained service animals will be allowed on any Delta flights if they are under 4 months old.

Delta says the changes take effect Dec. 18.

Exceptions will be made until Feb. 1 for customers who already bought a ticket and asked to bring a support animal.

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