The Seattle Times published a very informative article last Sunday (November 25) about "animal senior citizens" here at the zoo. Most people don't realize that many animals in zoos are geriatric, far outliving the "average" lifespan that they would in the wild. This is due to many factors including the simple fact they do not have predators, but also due to the advance veterinary medicine practiced in zoos. Older animals are still prone to many of the same things that humans are afflicted with: arthritis, cancers, et al, but with wildlife medicine constantly changing and evolving, they are leading fuller, active lives. Veterinary medicine practiced in zoos also often leads to advances in procedures, treatments and medicines that are used to help animals in the wild.
Check out the article and learn more about geriatric animal care: http://archives.seattletimes.nwsource.com/cgi-bin/texis.cgi/web/vortex/display?slug=zoo25&date=20071125&query=zoo