Seeing as all the animals died in the plague of pestilence, how could Moshe tell Pharaoh that the animals would be stricken with boils?
Rashi: Only their animals in the field died. Refer to 9:3:1:1 and the note there.
Refer to 9:6:151:2*.
Rashi said that only animals in the field died in Dever; the G-d-fearing Egyptians took his animals into the house. Regarding hail, it says that those ignored Hashem's word left his animals outside. Such a person's animals should have died in Dever!
Riva: Perhaps he feared Hashem at the time of Dever, but later soured, and did not fear at the time of Barad. Also, Dever is more prone to come than hail, so he was concerned only for Dever.
Perhaps he bought animals afterwards from Yisraelim or G-d-fearing Egyptians (PF).
Based on Ner Uzi'el: Most Egyptians realized that the Makos come like Moshe predicts, and took their animals into the house before Dever, even though they wreak havoc there. Before the hail, Moshe said "Shelach ha'Ez Es Miknecha
Why did they leave their slaves in the fields? They are not so terrible in the house! Perhaps the masters were proud of their ingenuity and confident that no harm would come, and left them in the barns to oversee the animals. (PF)
Rashi said that only animals in the field died in Dever; the G-d-fearing Egyptians took his animals into the house. Why does the Torah say so only about hail, but not for Dever?
Moshav Zekenim (9): One who was concerned for hail, which is bizarre, all the more so he was concerned for Dever, which commonly kills all animals (there was no need to write that the G-d-fearing Egyptians took their animals into the house before Dever). 1
According to the Ramban (refer to 9:3:1:2), there was no reason to enter them into the house. In any case they will die!
Based on Ner Uziel (refer to 9:10:151:3): For Dever, most realized that Moshe's predictions come true, and took their animals into the house. We find a distinction between them and those who feared Hashem's word only regarding hail.
Riva asked why the Torah did not say so about boils, and gave this answer. Perhaps there is a printing mistake; also he asked about Dever. Or, obviously boils are more common than hail in Egypt, so it was not needed to write so about boils. Or, oppositely - there was no danger from boils, just discomfort, so even the G-d-fearing Egyptians did not remove the animals from the field! - PF)