I have an older mare with a foundered front hoof. The mare stays shod year-round for comfort. I’ve been shoeing her for 3 years and it seems that within the last year, the hoof capsule is changing shape

I've recently been called to trim a horse and noticed that the hoof on the off-side front has separated from the coronet front by about 3 inches. After pointing out this problem to the owners, they told me that the horse was totally lame about a week prior and it's now sound and putting full weight on the foot. There's no sign of infection, and during trimming the horse shows no signs of discomfort. There's a lot of movement in the separation opening and you can see a sensitive area that appears to be healthy.