The following is not intended to be definitive, it's just general information. For a specific
diagnosis, ask your veterinarian.

It's possible to determine if a horse has foundered in the past with lateral radiographs.

Assuming the horse is asymptomatic and stable, if the coffin bone (P3) is parallel to the
dorsal surface of the hoof wall, then the horse has not foundered.

If the distance between P3 and dorsal wall is measurably greater at the distal aspect of
the bone and the transition is relatively uniform, then the horse has foundered at some
time in his life, most likely systemically and bilaterally.

If the distance between P3 and the dorsal wall is parallel at the proximal aspect of the
bone, then deviates abruptly from parallel at some point along the bone's dorsal surface,
then the horse has foundered at some time in his life, probably mechanically, either
unilaterally or bilaterally.

If the angle between the dorsal surface of P3 and the ground surface of the hoof is
greater than 60 degrees, then the hoof meets the textbook criterion for a club foot.
It is quite common for such feet to present with radiographic signs of chronic
mechanical founder.

The difference between systemic and mechanical founder has to do with the cause of
the change in P3's relationship with the wall: If the initial cause was laminetic dysfunction,
then the bone was pulled away from the wall by the deep digital flexor tendon; if the initial
cause was mechanical, then the wall was pulled away from the bone by mechanical forces.