ADA requirements specify that service animals (primarily guide dogs and some miniature horses) must be permitted in all areas of buildings open to the public, including areas normally restricted to pets. Service animals provide essential functions for persons with disabilities including guide services for blind individuals, alert services for persons with hearing impairments, and mobility assistance for persons with physical disabilities. Allergies and phobias regarding animals are not grounds for exclusion of service animals. Businesses may require that service animals be under control via leash or harness. Buildings must provide service animal relief areas outside the building for extended stays.