What happens next?

How to get paperwork on an employee's service animal
Confirm the existence of the employee's disability.
Under the ada, you can request medical certification from your employee. Your employee must bring a signed statement from a healthcare provider stating the nature of their disability.
Generally, if an employee wants to use a service animal in the workplace, they must come to you with a request to use that animal as a reasonable accommodation of their disability. Within this context, you may require your employee to present you with proof of the disability they claim to have.