chewing on Japanese Maple
Thank you for sending in the pictures. That definitely looks more like chewing than any other sort of physical damage. Based on the location, I'm thinking it might have been squirrels.
While any injury to the trunk is to be avoided, if the wounds visible in the 2 pictures are the only damage, the tree should recover on its own. You do not need to paint the wounds with any wound dressing: these products do not prevent decay or help the tree close off the wound.
If you see squirrels around this tree, try to wrap some chicken wire around the trunk to keep them off of it. Remember to loosen this up once or twice a year, to prevent girdling. You can also try to spray the trunks with animal repellent; any of the products in the garden center that list squirrels on the label should work. Be aware that repellents wear off quickly, especially in rain, and are a short-term solution at best.
Please let me know if you have any other questions.