To be betrayed or harmed by someone you trusted or took care of (literally: to have your hand bitten by your own dog).
部下に機密を漏らされてしまい、まさに飼い犬に手をかまれた気分だ。
My subordinate leaked confidential information, and I feel exactly as if my own dog had bitten my hand.
恩を注いだ相手に裏切られるのは、飼い犬に手をかまれるようで悔しい。
Being betrayed by someone you invested in is frustrating, like being bitten by your own dog.
彼は長年助けてきた同僚に足を引っ張られ、飼い犬に手をかまれる思いをした。
He was undermined by a colleague he had helped for years and felt as if betrayed by his own dog.