The Secretary shall issue licenses to dealers and exhibitors upon application therefor in such form and manner as he may prescribe and upon payment of such fee established pursuant to 2153 of this title: Provided, That no such license shall be issued until the dealer or exhibitor shall have demonstrated that his facilities comply with the standards promulgated by the Secretary pursuant to section
2143 of this title: Provided, however, That any retail pet store or other person who derives less than a substantial portion of his income (as determined by the Secretary) from the breeding and raising of dogs or cats on his own premises and sells any such dog or cat to a dealer or research facility shall not be required to obtain a license as a dealer or exhibitor under this chapter. The Secretary is further authorized to license, as dealers or exhibitors, persons who do not qualify as dealers or exhibitors within the meaning of this chapter upon such persons’ complying with the requirements specified above and agreeing, in writing, to comply with all the requirements of this chapter and the regulations promulgated by the Secretary hereunder.