United Airlines is joining other carriers in tightening its policies on emotional support animals.
Starting Jan. 7, the animals will not be able to travel on flight more than eight hours long.
In a statement, the airline said it has seen an increase in the number of on-board incidents with the animals, many of which are not used to spending a long time in the cabin of an aircraft.
United also will not accept kittens or puppies younger than four months as emotional support animals, in-cabin pets or service animals.
“Animals under the age of four months typically have not received the necessary vaccinations that help ensure the safety of our employees and customers,” the airline said.
United joins Delta Air Lines and Spirit Airlines in setting more restrictions on emotional support animals. Those two airlines require at least 48 hours’ notice to bring an emotional support or psychiatric service animal on a flight. They also require more documentation.
United implemented similar policies on March 1.
Previously, airlines have been more accommodating to such pets, only requiring that a passenger provided a letter from a licensed mental health professional to an airport agent on the day of travel.
Critics have said that mental health professionals have given out such letters too freely.
Passengers must pay a fee for in-cabin pets. But United does not charge for emotional support or service animals.
United is also limiting the acceptance of emotional support animals to dogs and cats. Acceptable service animals will now be limited to dogs, cats and miniature horses.
The airline will honor reservations made prior to today under the previous policy with the approved documentation.