Q. Since the horses were killed in the hail and fire Exodus 9:25, where do you reckon they got the horses for the chariots to pursue the Israelites? I know there is a good explanation, because every word He wrote is true. Also, is there any indication of how long the whole set of plagues took?
A. In Exodus 9:2 the Lord had Moses tell Pharaoh that if he didn’t release the Hebrews, a plague would come upon the livestock in the fields. Presumably animals in barns or stables weren’t harmed. It was the same in Exodus 9:25. Based on the Lord’s instructions (Exod. 9:22) the hail struck down men, plants, and livestock in the fields. But again those men and animals under shelter escaped. The most likely scenario is that the army’s horses were kept in stables, because with out them the army would have been immobilized.
While the Bible doesn’t specify the duration of time required for the 10 plagues to run their course, scholars have estimated that it took several months, perhaps as many as nine. They base this on various things, the flood stages of the Nile, the growing season, etc. Knowing that the 10th plague was memorialized by the Passover, which takes place in March/April, they then backed into an estimated start date using these factors as their guide.