Page 256 - The Veterinary Care of the Horse

some discomfort in the early stages. If the bone completely sinks, the depression will

extend around the whole length of the coronet (Figure 6.42)
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Figure 6.42 Feeling for a coronary band depression

• A coronary band discharge of serum may occur. In severe cases, haemorrhage and
serum from the damaged laminae may build up sufficient pressure within the foot to

escape at the coronary band.
• Change in hoof wall conformation As a result of ongoing studies, our understanding of

the reasons why the hoof wall becomes deformed has increased. Originally it was
thought that when the pedal bone rotates, its extensor process compresses the horn-

producing tissues of the coronet at the front of the foot. This slows down the rate of new
horn production at the toe. The result is laminitic growth rings which are wider at the

heel than the toe. The hoof changes shape, developing high heels and a long toe with a
concave anterior hoof wall (Figure 6.43). However, the changes in growth rate of the

hoof wall are now thought to begin in the developmental stage of laminitis, before the
pain begins. A faster growth rate at the heel causes the horn tubules to be distorted
forwards. This causes distortion of the sensitive laminae, resulting in pain. The forward