What does "va'Yamas Kol Mikneh Mitzrayim" mean?
Hadar Zekenim: Everything that died was from Egypt. Do not say that they all died
We find that the Egyptians had animals afterwards (See Pesukim 10 & 19)it is possible that they subsequently bought from Yisraelim or that the G-d fearing Egyptians sold their animals cheaply to Yisraelim before the plague, and bought them back afterwards for the proper price! (PF).