Laminitis
The equine foot is composed of the pedal bone and soft tissues, enveloped within the outer hoof capsule. The pedal bone (and all the weight it bears) is suspended within the capsule by strong tissues connecting it to laminae, which form the inner lining of the hoof wall.
What is laminitis?
Laminitis means inflammation of the laminae, which leads to failure of the structures that support the pedal bone within the hoof capsule. When these structures collapse, there is loss of the normal anatomical relationship of the pedal bone in relation to the hoof capsule. The degree of damage ranges from mild pain and reversible changes, to permanent damage to the foot.
Radiograph of an unaffected foot. Yellow lines represent the front of the hoof wall and the front of the pedal bone. These should ideally be parallel.
Radiograph of a laminitic foot with rotation of the pedal bone. The yellow lines are no longer parallel.
In the acute phase (the first 24-48 hours), the inflammatory process is at its peak and blood supply to the foot is usually compromised. Rotation and sinking of the pedal bone inside the hoof may be occurring.
In the chronic phase (from 24-48 hours onwards) pain usually decreases and radiographic (x-ray) evidence of rotation and sinking may be more evident. Pain across the sole of the foot may be increased and the pedal bone may in some cases be close to penetrating the sole.
Predisposing factors (to mention a few)
- Excessive highly-soluble carbohydrate in the diet (grains, lush grass etc)
- Retained afterbirth
- Excessive bodyweight
- Increased weight-bearing in one limb
- Severe colic
- Possible side effect of some drugs
- Genetic predisposition
Prevention
- Always feed a fibre-rich diet
- Minimise sudden dietary changes
- Aim to maintain an ideal bodyweight through feeding and exercise
- If one limb is out of action for prolonged periods, talk to your vet about protecting the opposite limb
- Suspect retained afterbirth? Get your vet in URGENTLY
- There are preventative treatments that can be used in situations where at-risk animals are exposed to lush grass eg FoundergardTM (A6863 P.A.R. Class I).
Treatment
Time is of the essence. Radiographs are useful to evaluate the degree of damage and monitor progress. In the acute phase the goal of treatment is to minimise pedal bone rotation, reduce sinking, avoid sole penetration and manage welfare with pain relief.
- Cool the limb for prolonged periods in an ice boot or cold water
- Provide a soft, accommodating surface for the animal to stand on. Sand is the best, followed by wood shaving, sawdust, straw or hay
- Therapeutic shoeing and trimming, aiming to shift weight from the toe to the heels.
- Anti-inflammatory pain relief
- Restricted movement
In the chronic phase the goal is to improve the disrupted relationship between the pedal bone and the hoof capsule via careful shoeing and trimming by your farrier.
A co-operative association between the vet and the farrier is the key to a successful outcome and remember that adequately treating laminitis can be a long-term and expensive process.
