The sole depth is also a critically important soft tissue parameter that can be measured easily and accurately on a true lateral radiograph. Studies report that most light-boned horses require 15mm of sole. An inadequate amount of sole can lead to compromised blood supply and subsequent soft tissue damage.
To measure sole depth, simply locate the apex of the coffin bone and draw a vertical line from the solar surface of PIII to the ground surface.
Note: If the horse is shod, draw the line from PIII to the top of the shoe.
The length of this line in millimeters is the sole depth.
In this case, the sole depth measures 4mm.
Sole Depth & Cup
Some horses will have a natural or man-made cup in their foot. This cup will appear radiographically as a radiolucent (black) area because it is an air pocket under the sole. To accurately measure sole depth, you need to measure the distance from the solar surface of PIII to the top of the cupped area. You then measure from the top of the cup to the ground surface or shoe, respectively.
In this case, the sole depth measures 9/6.