Does a guide dog have to be certified by the State to be an “official” guide dog?
No. Any guide dog, signal dog, or other animal individually trained to provide assistance to an individual with a disability.
Can a business owner insist on proof of state certification before letting a service animal into the business?
No. ADA regulations only allow animals to be excluded from a facility if it is a direct threat to the health or safety of other people or will disrupt the regular operation of the business.
For instance, a Dillard's department store in Texas wound up apologizing to a disabled military police veteran recently after he was asked to leave the store even though it was wearing a black vest with the words "service dog do not pet printed on it.