PIE *udhr and Etruscan thra 'breast'

From the Etruscan bronze mirror representing Hercules sucking June's
nipple (TLE 399): eca sren tva ichnac hercle unial clan thra sce, we
can infer Etruscan /thra/ 'breast'.

This word has obvious cognates in Sanscrit /udhar/, Greek /outhar/ and
Latin /uber/ 'breast', from PIE *udhr.