The Collaborative International Dictionary of English v.0.48:

Cynorexia \Cyn`o*rex"i*a\ (s?n`?-r?ks"?-?), n. [NL., fr. Gr.
   ????, ???, dog + ????? appetite. ] (Med.)
   A voracious appetite, like that of a starved dog.
   [1913 Webster]