Why did the prophet Isaiah mention breaking a dogs neck?

God there told his wayward people that their formal acts of worship not only failed to please him but actually caused his righteous anger to intensify because the worshipers were hypocritical. (Isaiah 1:11-17) In Isaiah 66:3 God now likens their offerings to heinous crimes. Their sacrificing a costly bull would no more appease God than would their murdering a human! Other sacrifices are likened to the offering up of a dog or a pig, animals that are unclean under the Mosaic Law and certainly unfit for sacrifice. (Leviticus 11:7, 27) God further shows that such crimes will not go unpunished!