Can the horse remove the grazing pan?

The Porta-Grazer has a clever locking system.

To remove the XL. Mini  or Corner Feeder grazing pan – align the keyhole in the side of the pan with the arrow on the barrel handle.

To remove the PG grazing pan- using two hands, simply lift the pan so that one side of the pan comes up thru the barrel opening, then give it a twist as you pull it up and out.