Pestilence

Then G-d sent a fatal pestilence that killed most of the domestic animals of the Egyptians.

How the people must have grieved when they saw their stately horses, the pride of Egypt, perish; when all the cattle of the fields were stricken at the word of Moses; and when the animals upon which they looked as gods died smitten by the plague! They had, moreover, the mortification of seeing the beasts of the Israelites unhurt.

Yet Pharaoh still hardened his heart, and would not let the Israelites go.