C. F. Keil and Franz Delitzsch on Exodus 9:6

Exo 9:6

In the words “all the cattle of the Egyptians died,” all is not to be taken in an absolute sense, but according to popular usage, as denoting such a quantity, that what remained was nothing in comparison; and, according to Exo 9:3, it must be entirely restricted to the cattle in the field. For, according to Exo 9:9 and Exo 9:19, much of the cattle of the Egyptians still remained even after this murrain, though it extended to all kinds of cattle, horses, asses, camels, oxen, and sheep, and differed in this respect from natural murrains.