Separation at the laminar interface reduces the strength of the coffin bone's attachment to the hoof wall and laminar separation often causes bleeding within the hoof capsule.
This combination of laminar destruction and hydraulic pressure within the dorsal portion of the hoof capsule when coupled with the constant downward pull of the deep digital flexor tendon can be strong enough to pull the coffin bone downward.
Why downward? The top (proximal) portion of the coffin bone pivots at the coffin (distal interphalangeal) joint. The deep digital flexor tendon, using the navicular bone as a fulcrum, flexes that joint each time foot flexes (turns over). If the attachment of the coffin bone to the wall is compromised, when the flexor muscles pull on the tendon, instead of the foot turning over, the coffin bone is pulled away from the hoof wall. The subsequent rotation of the coffin bone is called "founder".
After coffin bone rotation has been initiated, other factors occur which can cause the phenomenon to worsen, the most important of which has to do with the incompressibility of fluids. As the laminae are torn, bleeding occurs within the hoof capsule: because the dorsal hoof wall is the least flexible portion of the wall and the coffin bone is inflexible, the hydraulic pressure exerted by this blood flow often causes more tearing, more bleeding and more coffin bone rotation. When this occurs, instead of attachment loss at the laminar interface and the pull of the deep flexor being responsible for rotation, the bone is also pushed downward by the relevant hydraulics - in severe cases, through the sole.