The Chinese "moon'' bears, also known as Asiatic Black Bears, are covered with black fur and have a gold, sickle-shaped crest on their chests.
In China, more than 7000 of the bears are kept in tiny cages, with metal catheters implanted in their gall bladders so they can be regularly "milked'' for bile for use in traditional Chinese medicine.
Mrs Letham-White, a qualified veterinary nurse, recently returned to Dunedin after spending three months working as a volunteer with the Animals Asia Foundation (AAF) Black Bear Rescue Centre near Chengdu, in south-central China.
She described being so close to the centre's 166 bears as "an experience I will never forget".
"They are intelligent, playful, magnificent animals who get the very best of care that that the team can possibly give them,'' she said.
It had been a privilege to work with AAF's "amazing team of dedicated professionals'', which comprised Chinese staff, as well as overseas veterinarians, veterinary nurses and bear managers from the United Kingdom, Canada and Australia.
"The most difficult thing for me has been the knowledge that the bears AAF has rescued so far are only the tip of a very large iceberg,'' she said.
Bile farmers kept the bears in "tiny coffin-sized cages in which they can barely move, with no free access to food and water and suffering the cruel and unnecessary ordeal of bile extraction,'' she said.
Jill Robinson, the founder and chief executive of the Hong Kong-based AAF, recently urged the Chinese Government to give the bears their freedom to reflect the conservation-oriented spirit of the upcoming "Green Olympic Games''.
Mrs Letham-White said that bear bile farming had grown in parts of China, Vietnam and Korea since the 1980s.
That this "incredibly cruel'' practice should still be continuing was "beyond belief in the 21st century'', she said.
