Pathogenesis of Sole Lesions Attributed to Laminitis in Cattle

Introduction In cattle, lesions in the sole usually attributed to laminitis include haemorrhages in the horn, double soles, ulcers in the sole and toe, haemorrhage and separation of the white line, as well as deformation of the whole surface (“dropped sole”) (Ossent and others, 1997). Other authors used the term claw horn disruption (CHD) (Clarkson and others, 1996; Hoblet and Weiss, 2001). Usually these lesions occur in the heel, i.e. in zones 3, 4 and 6. The causes for CHD or laminitislike lesions are diverse. The incidence and severity of the lesions are influenced by external mechanical factors such as abnormal claw or limb configuration, hard surfaces and soft horn. Systemic factors are associated with rumen acidosis, ketosis and endotoxaemia due to e.g. inadequate feeding. In analogy to the situation in the horse, the pathogenesis has been associated with systemic insult to the microvasculature in the pododerm in conjunction with laminitis. Due to the initial collapse of the suspensory apparatus within the laminar region of the claw the pedal bone sinks within the horn capsule and compresses the underlying corium to produce so called "phase 3 lesions". The theories on pathogenesis and aetiology have been described in detail by Ossent and others, (1997).