I've been told by vets and farriers to avoid sand & DG as much as possible. Sand colic
and dry feet in the dry months and small rocks working there way up the white line of
the feet and causing problems are the reason. It's a tough problem to solve. I have a
sandy area to put my horses in when the rain is too much. Then as soon as it is
acceptable elsewhere I move them out of the coarse sand area.
The comment about shavings is good but be careful accepting random wood chips and
shavings. Some trees and wood have compounds that are toxic to the horses.
Jim Mitchell
Bakersfield, Ca. Where it is raining but we don't get anything like northern Calif.