The ADA requires businesses to allow people with disabilities to bring their service dogs with them into their facilities. This does not mean that a business isn't permitted to have a “no animals allowed” policy. Rather, a business that has a "no animals" policy must make an exception or modification to the policy for people with disabilities who use service dogs.
A public entity or private business must allow a person with a disability to bring a miniature horse on the premises as long as it has been individually trained to do work or perform tasks for the benefit of the individual with a disability. However, an organization can consider whether the facility can accommodate the miniature based on the horse's type, size, and weight. The rules that apply to service dogs also apply to miniature horses.
These questions may not be asked if the need for the service animal is obvious (e.g., the dog is guiding an individual who is blind or is pulling a person's wheelchair). A public entity or private business may not ask about the nature or extent of an individual's disability or require documentation, such as proof that the animal has been certified, trained or licensed as a service animal, or require the animal to wear an identifying vest.