Laminitis

LAMINITIS.
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DEFINITION.

Laminitis is not an inflammatory condition of the foot per se but a peripheral vascular disorder caused by either systemic disease and or chronic overloading of a single limb (like in the case of fractures of the opposing limb). The Equine foot appears to be a target for vascular abnormalities due to the unique disposition of the blood vessels within a non expandable hoof capsule. Pony breeds seem to be more predisposed to laminitis.

PATHOGENESIS, AETHIOLOGY AND CLASSIFICATION.

The alterations in vasoactive mechanisms lead to laminar ischaemia in the horse’s foot, developing necrosis in the structures of the hoof wall specially the dorsal aspects of coronary band, hoof wall and sole. The resulting pain causes further release of catecholamines that cause vasoconstriction and further ischemia, thus oedema forming at the epidermal-dermal junction allowing the support of the pedal bone within the hoof capsule to be lost, due to weight bearing and the pull of the deep digital flexor tendon mechanical separation occurs mainly in the toe region, with the pedal bone rotating or sinking.

The Causes are multifactorial as many different predisposing factors can trigger the same vascular mechanism. Will divide them into 4 main categories.
Alimentary: Grain overload, Grass overload, Cold water ingestion and Electrolyte imbalances.
Single Limb overloading: in severe unilateral lameness
Hormonal: Corticosteroid overloading, high testosterone and oestrogen, Hyperthyroidism, Hyperadrenocorticism and Cushings.
Endotoxic: as a sequel to colic, pneumonia, metritis….

We have 3 presentations, Acute (acute phase of systemic illness with lameness) Chronic (residual lameness following resolution of systemic illness) and Chronic laminitis not associated with any active disease but concurrent to chronically distorted feet.

CLINICAL SIGNS.

Acute laminitis. Pain and lameness concurrent with signs of the systemic disease. Other signs will...