The US government has indicated that when it is not obvious what services an animal provides the business can only ask two questions of the owner:
(1) is the dog a service animal required because of a disability, and
(2) what work or task has the dog been trained to perform.
There are some specific things that cannot be asked per the revised ADA requirements at https://www.ada.gov/service_animals_2010.htm
That document states the staff cannot ask about the person’s disability, require medical documentation, require a special identification card or training documentation for the dog, or ask that the dog demonstrate its ability to perform the work or task.
These two publications provide almost all of the information that is required for a business when addressing the issue of service animals, although the requirements are gradually changing:
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