Kotowaza of the day: Man's best friend?

Japanese:

飼い犬に手を噛まれる

Romanized:

Kaiinu-ni te-wo kamareru

Meaning of Japanese:

To get bit by one's own dog
To get backstabbed/be betrayed

English equivalents:

Man may cause his own dog to bite him
Caress your dog and he'll spoil your clothes

Related:

Don't bite the hand that feeds you