No person shall keep, shelter or harbor any dangerous animal as a pet, or act as a custodian for such animal, temporarily or otherwise, or keep such animal for any other purpose or in any other capacity within the City except in the following circumstances:
1. The keeping of dangerous animals in a public zoo, bona fide educational or medical institution, humane society or museum where they are kept as live specimens for the public to view or for instruction, research or study.
2. The keeping of dangerous animals for exhibition to the public by a circus, carnival, exhibit or show where such circus, carnival, exhibit or show is of a traveling nature, is displayed before large assemblages of people, and maintains all required Federal or State licenses.
3. The keeping of dangerous animals in a bona fide, licensed veterinary hospital for treatment.
4. The keeping of dangerous animals by a wildlife rescue organization in accordance with rules established by the Natural Resource Commission.