LAMINITIS.

Causes of laminitis:

Laminitis may develop with no obvious predisposing factors, but in most cases it is caused by one of the factors below:
• Lush spring grass (especially ponies)
• Dietary change increased amounts of carbohydrate, grain overload leads to laminitis in most cases
• Cushings disease in old horses and ponies.
• Shock (endotoxemia and/or dehydration) due to Colic, Colitis, Metritis or Pneumonia
• Septic metritis after foaling leads to laminitis in most cases, making this disease an emergency to treat.
• Trauma due to increased concussion during exercise (prolonged exercise on hard surface).
• Weight bearing limb due to injury in opposite limb.
•  Trauma due to increased concussion during exercise (prolonged exercise on hard surface).

Clinical signs of laminitis:

• Shifting weight off front feet onto back feet as shown in the picture below.
• Increased heat in feet.
• Bounding digital pulses.
• Pain in the hoof.
• Will not allow foot to be picked up.
• Reluctant to walk
• May be down and will not get up until forced.

Results of laminitis:

• Destruction and dysfunction of the cells in the hoof begins hours before the lameness is apparent
• Death of cells of secondary laminae results in separation of sensitive and insensitive laminae. The laminae hold the hoof to the bone (coffin bone).
• Coffin bone detachment from hoof wall to a varying degree this causes rotation or sinking of the pedal bone or both of these changes – see below.
• The horse has chronic pain from the displacement of the pedal bone.
 The hoof becomes misshapen due to growth at toe and lack of growth at the heel. Growth rings become prominent and the sole becomes flattened.
• Horses and ponies with chronic laminitis are prone to recurring foot abscessation, hoof cracks and chips and a tendency toward sole bruising.
• In severe cases there may be complete separation of hoof from foot capsule, which usually necessitates euthanasia.

Rotation of the coffin bone:

Treatment:

1. Medical therapy to control the inflammation and pressure on the tissues inside the hoof.
2. Mechanical support using frog supports and deep bedding.
3. Box rest.
4. Assessment of the changes in the foot i.e. sinking or rotation of the pedal bone by taking X-Rays.
5. Long term support using a heart bar shoe may be required as shown below:
 

Long term management:

• Phenylbutazone as needed at minimal doses.
• Soft ground
• Mechanical support e.g. heart bar shoe.
• Regular attendance by the farrier to correct the foot balance.
• Correct nutrition (please ask us for advice).
• Avoid having an overweight animal.
• If rotation occurs, the prognosis for return to previous level of exercise is guarded to poor.
• Sinking creates a worse prognosis.
• Without rotation and sinking horses may still experience prolonged alteration of hoof growth with tendency toward cracking, sole bruising, abscesses etc. that can lead to recurrent lameness.