Exodus 9:6-9

6And the next day the Lord did it: All the livestock of the Egyptians died, but not one animal belonging to the Israelites died.

7Pharaoh investigated and found that not even one of the animals of the Israelites had died. Yet his heart was unyielding and he would not let the people go.

8Then the Lord said to Moses and Aaron, “Take handfuls of soot from a furnace and have Moses toss it into the air in the presence of Pharaoh.

9It will become fine dust over the whole land of Egypt, and festering boils will break out on people and animals throughout the land.”