Laminitis

Eleanor Storey BVM&S MRCVS, St David’s Equine Practice

With this spring grass, Laminitis is on every owners’ mind. We lose a number of horses to it every year, yet whilst it is very common, it is also still incompletely understood.

Signs vary from marginal discomfort to severe lameness where the horse or pony spends prolonged periods lying down. In general, the faster and the more aggressive the treatment the better the prognosis.

The pain that is experienced during a laminitic episode is due to inflammation of the soft tissue ‘leaves’ that suspend and support the pedal bone within the hoof capsule. If the inflammation is not controlled, this rapidly leads to irreversible damage to the laminae preventing them from doing their job. This allows the pedal bone to start pulling away from the normally strong and elastic laminae as the tip of it starts to head towards the sole of the foot. This rotation is caused by the pull of the strong flexor tendon which runs down the back of the leg and inserts onto the back of the pedal bone.  As the tip of the pedal bone starts to rotate down towards the sole the pull on the laminae increases and the pain the horse experiences continues. At this stage, anti-inflammatories and pain relief become less effective as the pain is not just being caused by inflammation – it is being caused by the damage being done to the laminae and the constant pull on those laminae from the rotated bone.

Radiographs are vital in determining whether there has been any abnormal movement of the pedal bone and enable the vet to prescribe the most appropriate treatment.  Horses with rotation of the pedal bone require intensive nursing and remedial farrier to have any chance of becoming sound again. Sadly this often requires significant financial input and long periods of time confined to a stable which may not be tolerated well by the horse.  We aim to treat laminitic cases before the pedal bone starts moving and this requires the owner reporting the early signs of the disease.

Why would my horse get laminitis?

Any horse can develop laminitis.  Many owners feel that lush pasture is responsible for causing laminitis, but the situation is not that clear. The problem is almost always due to the horse rather than what the horse is eating. The vast majority of horses develop laminitis as a result of being unable to tolerate sugars in the diet. Metabolic Syndrome and PPID (Cushings Disease) are the two main reasons why they wouldn’t be able to tolerate sugars.

What can we do to prevent laminitis?

Test for Cushings Disease

Test for Metabolic Syndrome

Regular foot trimming by a registered farrier to ensure feet are kept in the correct shape. Longer toes predispose a horse to laminitis due to the mechanical forces being applied to the structures within the foot.

Do not allow your horse to become overweight. An overweight horse is at much greater risk of developing Metabolic Syndrome.

How can I recognise the early signs?

In mild cases, the horse may appear slightly ‘pottery’.  They are commonly more uncomfortable walking down sloping ground, stony ground and when asked to turn tightly.

The forelimbs are most commonly affected although it is possible for the hind limbs only or all four feet to be affected. Often one foot is worse than the others.

The affected foot or feet may appear abnormally warm to the touch and the pulse taken at the heel’s arteries may appear particularly strong.

Severely laminitic horses will often stand with hind limbs well under the body and forelimbs stretched out in front. Affected horses may also move with their heels landing first to try to avoid concussion to the painful toe region. If all four feet are affected, they may lie down for long periods or may constantly lift their feet alternately.

Horses which have suffered chronic or ‘subclinical’ (undetected laminitis) will have evidence of abnormal hoof growth with heel growth being faster than toe growth due to deformity of the structures within the hoof capsule. This is most easily spotted with ‘rings’ of growth being wider apart at the heel of the foot compared to the front of the foot.

When to call the vet

Acute laminitic inflammation can progress to severe laminitis with pedal bone rotation within a matter of hours. We always treat laminitis as an absolute emergency.

Your horse should be stabled as soon as laminitis is suspected.  Ensure your horse has a deep bed up to the front of the door.

St David’s Equine Practice is providing the equine veterinary services for Molecare Veterinary Services in the South Molton, Newton Abbot and Cullompton areas. For more information, visit www.stdavids-equine.co.uk