Proof of disability – Physical examinations. Proof of duty, occupational disease, or ordinary disability shall be furnished to the board by at least one licensed and practicing physician appointed by the board. In cases where the board requests an applicant to get a second opinion, the applicant must select a physician from a list of qualified licensed and practicing physicians who specialize in the various medical areas related to duty injuries and illnesses, as established by the board. The board may require other evidence of disability. A disabled policeman who receives a duty, occupational disease, or ordinary disability benefit shall be examined at least once a year by one or more physicians appointed by the board. When the disability ceases, the board shall discontinue payment of the benefit, and the policeman shall be returned to active service.