Definition
This idiom is used to question why someone would do something themselves when they are already paying someone else to do it.
You've hired a cleaning company, so why are you still sweeping the floor yourself? It's like, why keep a dog and bark yourself?
The company hired an accountant, but the boss is still doing the taxes himself. It’s like, why keep a dog and bark yourself?
Since you paid for the contractor, why are you painting the walls yourself? It's like, why keep a dog and bark yourself?