Laminitis is the inflammation and subsequent break down of the lamellar attachment which is the bond between the pedal bone and the hoof wall.
The lamellar attachment is formed by lamellae, finger like projections that work similar to the bond formed in Velcro to hold the hoof wall to the soft tissue and the pedal bone of the foot. Laminitis can be triggered by many conditions in the horse. These can be grouped as Hormone Associated (i.e. Equine Metabolic Syndrome, Equine Cushing’s Disease, changes in metabolism in late pregnancy), Sepsis Associated (i.e. pneumonia, diarrhoea, retained foetal membranes after foaling) or Mechanical (i.e. supporting limb laminitis and ‘road founder’).
Once a horse has suffered an episode of laminitis, it is more likely to suffer subsequent episodes. For this reason, it is very important to monitor all horses which are known to have had previous laminitis episodes for any signs of lameness or foot soreness. Clinical signs of laminitis include frequently shifting weight, palpable digital pulses of the affected limbs, changes in the growth pattern of the hoof capsule and pain when using hoof testers. Horses with laminitis are typically lame, however their lameness can range from mildly lame at the trot or poor performance, to noticeably lame at the walk, to very severe cases where the horse cannot move or is lying down.
Along with the clinical signs, the use of radiographs can be very helpful in diagnosing laminitis and is very important in guiding treatment. To gain even further information, a venogram can be performed. This procedure involves injecting a dye into the vein supplying the foot and then taking a series of radiographs. The dye is visible on radiographs and allows the veterinarian to determine the extent of the damaged tissue and the remaining blood supply to the foot.