I always like reading about Koko as she (to me at least) proves that non-human primates could communicate as well as humans given the chance and means.  Well, apparently she was able to convey tooth pain and got a whole battery of medical exams!

Link:

http://news.bbc.co.uk/cbbcnews/hi/animals/newsid_3549000/3549314.stm

(I find it amusing that when one of the specialists gave her a business card, she ate it !)

Kat