After months of deliberation, the Department of Transportation has released formal guidance regarding animals on planes. The 28-page document released this month makes it clear that three types of service animals should be prioritized for travel: cats, dogs and miniature horses.

Yes, miniature horses. The document repeatedly includes mini horses in a trio of “the most commonly recognized service animals” and the “most commonly used service animals.”

Q: Why a mini horse?

A: There are many reasons someone would fly with a miniature horse, disability experts say. Although a growing number of emotional support animals have emerged in recent years, in the case of miniature horses, their function as service animal is primarily physical, said Kenneth Shiotani, a senior staff lawyer at the National Disability Rights Network.

For some blind people, guide horses serve as a compelling alternative to guide dogs. The animals are mild-mannered and fast learners, with nearly 360-degree vision. They may also offer balance support to individuals with physical disabilities.

Mona Ramouni, who has more experience traveling with a miniature horse than perhaps anyone else in America, pointed out that training a service animal takes thousands of hours. “With a dog you’ll get eight to 10 years if you are lucky,” she said, adding that “with a horse you get 35, 40 years.” Ramouni’s own horse, Cali, is 14. “She’s just getting to middle age,” she said.

Q: How do you get a horse to the airport?

A: True miniature horses, which are not to be confused with ponies, are less than 34 inches in height.

Their compact size makes them capable of fitting into the back of a hatchback, which is how Ramouni and her husband typically get Cali to the airport. “She’ll jump into the back of the car,” Ramouni said.

Q: How do you get the horse on the plane?

A: Ramouni usually buys flights on short notice, calling the airline the day before to give a heads-up that she will be traveling with a horse. Occasionally airlines have told her that they did not have room, she said, but she is hopeful that the new guidelines will discourage such responses.

Going through security with Cali tends to prompt giggles and declarations from workers that “I’ve never checked a horse before.” Airport officials will sometimes ask for Cali’s official “horse ID,” Ramouni said. Unaware of any organization that offers such a thing, she and a friend eventually made a card themselves.

Before going to the gate, Ramouni will ask someone to lead them to the women’s restroom. “My horse has been trained to go potty in a plastic bag,” she said. “I would just give her the command to go potty, then I flush it down the toilet.”

Q: How do you fit a horse in front of your seat?

A: Airlines have typically put Ramouni and Cali in the bulkhead row, which has more legroom and no seats in front. Throughout the flight Cali stands at Ramouni’s feet.

On the way down, Ramouni gives Cali ice to chew for the pressure. She doesn’t like to fly too often — or for too long — because she knows that flying is hard on horses.

Ramouni said she was hopeful the new regulations would encourage other people to fly with their guide horses and, in doing so, would help make a case for guide horses over guide dogs. The next frontier, she said, is international travel.