If we were writing, we'd use commas, parentheses, or even dashes to separate this additional information and mark it off as an independent thought group.
Along yet another corridor he dashed, and then there were owls everywhere, and Mrs. Norris was hissing and trying to bat them with her paws, no doubt to return them to their proper place. . . .
As he was, like many squirrels, full of courage and dash and energy and excitement and mischief (not to say conceit) , he no sooner heard it than he was eager to be off.
There are swift-flowing rivers which dash through jagged canons; and there are enormous plains, which in winter are white with snow, and in summer are gray with the saline alkali dust.