May 13 (Reuters) - Canada’s main stock index opened slightly higher on Thursday, as gains in healthcare and consumer discretionary stocks offset losses in the energy sector. * At 9:34 a.m. ET (13:34 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was up 10.35 points, or 0.05%, at 19,118.12. Reporting by Shivani Kumaresan in Bengaluru; Editing by Devika Syamnath Our Standards: The Thomson Reuters Trust Principles.