It looks like one of the dogs gouged a deep scratch into one of the thresholds I slaved over about half a year ago. I used finish screws to install the thresholds, so I am thinking to just pick the piece up, take it to the shop and reapply a coat of finish (I used Bush Oil, a commercial blend of the 1/3 each tung oil, BLO and urethane mix).

Should I reapply finish just to the scratched area or also to the entire visible portion of the piece?

Should I plan on adding a coat of finish to each of the transition pieces?

Since these guys are, essentially, the floor, is there a good strong, hard and scratch resistant clear coat I could use after touching up these scratches that can go over an oil / urethane finish? That bowling alley stuff perhaps?