The fifth plague was against the livestock. As with the withholding of flies from the area where the Hebrews lived (8:22–23), the distinction between the livestock of the Israelites and that of the Egyptians (9:4) shows that a natural explanation of this event is insufficient, even if the previous plagues contributed.
The Egyptians, like many in the ancient Near East, worshiped the ram, the goat, and the bull as representing power and fertility. These animals had no power before the Lord, in whom true power resides.