Samantha--Sandeater!

Round about 2 months or so, I found that Samantha had become a Sandeater, and ever worse, a Dedicated Sandeater. She would stroll around the arena, taking in large mouthfuls of sand. I tried moving her to a less sandy pen but she just found the sand and continued to devour it. For the night, in desperation, I shut her & Rebecca into a stall that had stall mats. The next day, I had delivered a truck load of more stall mats. The stall had a 10' x 20' pen off of it and I was going to stall mat the entire thing. The barn supply truck stacked up the mats right near the pen's back gate & I went to work, dragging those 100 pound mats into place in the pen. Once done, I opened the stall door and let them out. Samantha promptly checked for a spot with sand but she could not find a weakness to exploit in her hunt.
Since young horses need space to run, I got her & Rebecca out into the arena twice a day, every day for a run. Rebecca had a good roll and Samantha would run--until she ran off some energy then started the search for sand. Then I got to run after her and get her moving again. I had also started spooning psyllium into her mouth to clean out what sand she had already gotten and what she was still managing to get. The results of the first day of that was dramatic. Her poop the next day was the unique charcoll gray color of heavy sand. She did not especially like eating the psyllium, but did not really fight it either and most of what I spooned into her mouth did go down into her.
So we all survived. She was weaned at about 5-6 months and then I had to figure out a new way to exercise her as I was now doing more running then her.