I agree with Face (WOW!!!!) its possibly a mineral deficiency especially as the horse is kept on a sand paddock and not on dirt/grass which is really what is natural for them - many of the places we keep horses in would not have been places where horses would live or survive naturally
I keep good quality mineral licks all over the place but the only two that bothered with them were the new mares that had previously been kept on small sand paddocks - they almost ate them at first and now I notice after a while with us and being able to go on reasonable acreage of grass barely touch them at all
The only other thought is boredom and digging alleviates that and presents a challenge - that might tie in with the fact you haven't been able to work as normal
I am in the desert, so no grass. The area they are primarily kept was sanded for the comfort of a past senior. But, as soon as the weather is kinder, I will be taking notes to see if being worked slows her digging down. She does love
to be worked with, no matter the difficulty or "frustration" level. The "I am bored, come work with me or I will run away to China" sounds like something she would pull. Until I got her, I never had a youngster that wasn't allowed to just be a horse (run free) until it was well into its second year, however, she was kept in a small paddock during her entire second year. I will NEVER make that mistake again - horses raised like that are missing more than minerals! :) While I love her and she is easy, easy to train, she has the oddest and some of the most annoying behaviors I have ever dealt with..including this one! But as usual, I will give her the benefit of the doubt and try to "address" it. :)
I've seen colts dig big holes in their pens (craters) overnight after being gelded.....could possibly be a pain response......just like some people pace around when they're in pain, horses will dig!
She shows no signs of pain (very playful w my mare, runs about and has a healthy
appetite). I don't think she is in pain, w the possible exception of the emergence of her bottom incisors. But, I will look to see if it is a possibility.