We had a cross between a
beaver and a horse here that ate through boards like a buzz saw. Finally
ended up capping the stall doors and the fence around the paddock with
DWV PVC pipe.(drain waste and vent is the thick stuff) Take 21/2" or
whatever inside dimension pipe fits the board and split it on a table
saw, a fine tooth plywood blade works good. Drill holes for screws, cut
to length and screw it down. Be sure to counter sink the screw heads or
they stick up and can chip a tooth. She did end up chewing through a
treated post out of frustration but the boards are still
there.