It probably wasn't. But, it probably was claimed to be.
As someone who suffers from a plethora of health problems that I've seen people have "service/therapy" animals for it makes me want to scream. I have come to the realization everyone feels they are special and deserve special treatment.
That is not to say that there are not people who genuinely do need animals for help. And, I'm not saying that all of the animals come in the same package. It's just becoming ridiculous.
Also, as someone who has spent her entire 27 years of life around Miniature Horses, they shouldn't be used as service animals. They are prey animals, and the situations people put themselves in with them can be stressful for the horse and even dangerous. That makes me want to scream too. Especially, because the ones you see used for that are dwarfs and have health problems.
Oddly enough, since you have experience with horses, you'd be a perfect candidate for a guide horse if you were blind.
http://www.guidehorse.org/ says:
Who is the Ideal Guide Horse Owner?
The Guide Horse Foundation has had exceptional interest from the following types of people:
*Horse lovers - Blind people who have grown up with horses and understand equine behavior and care are ideal candidates.
*Allergenic people - Many people who are severely allergic to traditional guide animals and find horses a non-allergenic alternative for mobility.
*Mature Individuals - Many people report difficulty dealing with the grief of losing their animals, and horses tend to live far longer than traditional guides.
*Physically Disabled folks - Because of their docile nature, Guide Horses are easier to handle for individuals with physical disabilities. They are also strong enough to provide support, helping the handler to rise from their chair.
*Dog Phobia - Individuals who fear dogs are often comfortable working with a tiny horse.
*Outdoor Animal - Many individuals prefer a guide animal that does not have to live in the house when off duty.
As for being unable to manage stressful situations - I'm wondering how do the working horses I see in my city every day manage? They're carrying cops, putting on shows, pulling carriages, occasionally even helping break up riots/protests... They seem to cope happily enough. Are miniature horses more temperamental and high-strung than the full-sized variety?