、。
On my way to school every day, I see a dog.
Literal
Every-day school [to-に] go way-in-the-middle [at-で], I [topic-は] dog [object-を] catch-sight-of.
途中で ('on the way, in the middle of') marks an event as occurring during the course of a journey. 目にする ('to set eyes on, to catch sight of') is a common idiom for incidental observation — slightly more literary than 見る. The ~途中で[X]を目にする pattern (path + observation) is widely used to describe things noticed in passing.