Today's zoo veterinarian serves as both doctor and defender, as UC Davis wildlife veterinarians Ray Wack and Scott Larsen can testify. Wack and Larsen, the attending vets at the Sacramento Zoo, also serve on the faculty of the UC Davis School of Veterinary Medicine.

Wack and Larsen are featured in a new documentary airing tonight (7 p.m.) and Sunday (6 p.m.) on "Viewfinder" on Sacramento PBS affiliate KVIE-TV (Ch. 6).

Produced by the UC Davis News Service for KVIE, the program explores the important role that zoos are playing in wildlife conservation and how veterinarians and conservation experts are debating big questions about the issues:

• Are zoos safe for both animals and humans?
• Are they still places to educate and inspire?
• Or, as some activists claim, are zoos cruel and unnecessary prisons for wild creatures?

Three zoos on the West Coast offer answers. They include the San Francisco Zoo, which is still responding to last December's tiger escape when one teenage visitor was killed and his two companions injured.

Wack and Larsen discuss how their role as zoo docs -- caring for animals and helping to manage zoos and their animal populations -- is growing more challenging and complicated each year.

Joining them in the video are Mark Schwartz, a nationally recognized conservation ecologist from UC Davis; Murray Fowler, a UC Davis professor emeritus of veterinary medicine widely regarded as the father of zoo medicine; and Jane Goodall, the world's foremost authority on chimpanzees.

New Service reporter Paul Pfotenhauer and freelance videographer Ken Zukin also visit Seattle's Woodland Park Zoo to see how it has made a major commitment to field conservation.

For more information about "Captive Audience," including a Windows Media Player version of the program and video extras not aired as part of the documentary, visit http://www.ucdavis.edu.