there are four kinds of bows: high, low, middle, and classic which is all 3.
How long ago did he initially bow? What did they do to treat it?
Horses typically always bow again if its not treated agressively the first time and if they have not had enough time off.
My thoughts on this: use supports like brace bandages, not boots. Boots are for protection, not so much support. Brace bandages are made to support. Especially with issues like bows, suspensories, etc.
If you do see sorness, use heat, not cold. Using paints like some ball solution with a bit of cedar oil and DMSO will bring heat to it. After a bow has initailly been treated, cold water hosing and cold treatments don't do any good anymore. When a bow occurs you want to apply cold and pressure to stop the fluid from building. But once a bow is a bow use heat.
If there is any re-bowing, or severe lameness, I suggest using a 5 day water blister. You put it on the first day and scrub it in, day 2 you hand walk 15 min, day 3, 4, and 5 you put on cold water hoses for 15 min 2 times a day. I would leave them on stall/paddock rest for atleast 6 months and blister 3 times before bringing them back to work AT ALL.