Page 257 - The Veterinary Care of the Horse

distortion of the hoof capsule results in the anterior hoof wall being lifted away from the

underlying sensitive laminae starting closest to the ground and gradually working
VetBooks.ir upwards. The result is a concave anterior hoof wall. It is suggested that the trigger factors
initiating laminitis also trigger the faster growth rate of the hoof wall at the heels and that

the pain of the acute stage of laminitis is due to the distortion of the sensitive laminae
which occurs before any changes can be seen in the actual appearance of the hoof wall.

The ‘dorsal wall lifting’ theory proposes that the lifting of the anterior hoof wall also
pulls the sole upwards causing compression of the circumflex artery under the front of
the pedal bone thus compromising the blood supply to the foot.

Figure 6.43 Laminitic growth rings are wider at the heel than at the toe

• Change in sole conformation The normally concave sole may become flat or even

convex as the pedal bone rotates or sinks within the hoof capsule. The pedal bone may

begin to penetrate the sole. This will show as a semicircular area of bruising before the
sole is actually penetrated (see Figures 6.40a and b).
• Increased width of the white line In the chronic stage, there is often a widening of the

white line at the ground surface due to excessive amounts of horny tissue being