I'm going to get a kitten this spring/summer (maybe today!), and I was interested in registering her as an ESA. I did a bunch of research, as did my therapist (who was willing to do the letter for me). It turns out that Emotional Support Animals don't truly grant you much in the way of rights and/or exceptions (having your pet in a hotel room, taking it on a plane with you, getting an exception if your renter doesn't allow animals, etc.) Hotels, airlines, and other businesses reserve the right to deny you from bringing your animal onto their property.

Service animals are the only ones that can provide those type of rights and/or exceptions. As of now, only two types of animals can be registered as Service animals - dogs and miniature horses. You have to be able to prove that your Service animal provides a very specific purpose for you (i.e. alert to sounds if you're deaf, bring certain items that you aren't able to access, alert to the onset of a seizure, etc.) If you have a dog or miniature horse as a certified Service animal, there is a law that requires property owners to allow you to have your animal in your abode without discrimination or extra pet deposits.

There are websites out there where, for a fee, you can get certificates and even kits (include vests, leashes, carriers, and so forth that visually ID your pet as an ESA or Service animal). But, if your pet is not officially recognized and verified as a Service animal, and you get asked for proof, your animal may be turned away.

I hope this helps. I spent a ton of time checking into this.