'Emotional Support' Pig Kicked off Plane: Why Are These Animals Allowed on Board?

Daniel Munoz walks his pig Gusfredi at a park in Mexico City on October 15, 2015. At first glance, they might seem like small, pudgy dogs, but they are really mini pigs being walked, the latest pet fashion and status symbol in Mexico City. The pig on the plane was also a companion animal, but even mini pigs can grow to be hundreds of pounds. RONALDO SCHEMIDT/AFP/Getty Images

Reports have resurfaced about a woman flying on US Airways who was kicked off a flight with her companion—a 300-pound pig.

If you've read this story, take note that the initial ruckus actually took place in 2000, with a second pig-plane controversy following in 2014. The incidents may have occurred years ago, but the issues they raised remain just as thorny today: Misconceptions still swirl regarding the definition and rights of a service animal and an Emotional Support Animal, or ESA.

According to ABC News, the pig managed to make it on the plane in the 2000 incident after its handlers convinced the airline that he was a medically necessary animal, and gave them what appeared to be a doctor's note. When the animal began squealing and walking up and down the aisle, airline workers decided the pig was causing more distress than comfort and removed the animal and its owner.

This incident inspires a flurry of questions. Can a pig really be classified as an Emotional Support Animal? Do such animals have legal rights to be on planes? How do you get certified? The answers are complicated.

For starters, yes, animals other than dogs, including pigs and even squirrels, can be classified as ESAs. However, there is increasing controversy about what rights an ESA should have, if and how that title should be regulated and to what extent airplanes should accommodate them.

There is no legal registry or certification of ESA. If you search the Internet for "Emotional Support Animal," you will see several ads for companies willing to relieve you of your money for an official-looking but legally inconsequential document stating that your animal is a Service Animal or Emotional Support Animal. ESAs, which can be any species, do have legal protection under the Fair Housing Act and only require a letter from a doctor. However, that doesn't mean that an airline or a restaurant has to honor your request to bring it in.

A Certified Service Animal is quite different. Although anyone can write "service animal" on a bandana and put it on a bearded dragon, the U.S. Americans with Disabilities Act officially recognizes only dogs, and in some cases miniature horses, as eligible for service animal certification. They must also be trained to perform a specific task, like guiding the blind or alerting their owners of an upcoming seizure. Service animals have more protections than ESAs, as many people physically require them to help them deal with their disabilities.

One might think that the TSA would stop a pig from going through a security check. However, the job of the TSA is not to stop you from taking items like pets or even stolen goods or drugs on a plane. They're there to stop you from taking items that are or look dangerous. Pets have to be screened just like humans, but the TSA is not charged with telling travelers what kind of non-dangerous pet belongs on a flight.

No laws restrict who can and cannot put a nonhuman animal on an aircraft. Larger animals like livestock would require special planning and can't enter the cabin, but they do fly. Customs for international flights have restrictions on things like invasive species, though.

As for US Airways, after the pig incidents, airline workers said that in the future, they would no longer let farm animals in the cabin.