Exodus 11:5-7

and all the firstborn in the land [the pride, hope, and joy] of Egypt shall die, from the firstborn of Pharaoh who sits on his throne, to the firstborn of the slave girl who is behind the hand-mill, and all the firstborn of cattle as well. There shall be a great cry [of heartache and sorrow] throughout the land of Egypt, such as has never been before and such as shall never be again. But not even a dog will threaten any of the Israelites, whether man or animal, so that you may know [without any doubt] and acknowledge how the LORD makes a distinction between Egypt and Israel.’