Presence of receptors for epidermal growth factor (EGF) in the matrix of the bovine hoof--a possible new approach to the laminitis problem

The digital pathologies of chronic laminitis

This review indicates that the patient-to-patient uniqueness commonly seen in chronic laminitis represents the variable presence of the digital pathologies. Although some degree of mechanical failure is always present, the secondary metabolic and growth dysplasias, vascular pathologies, and sepsis may or may not be evident. The presence and severity of these pathologies appear to have a more significant impact on the prognosis of individual cases than does the displacement of the distal phalanx. It should be reiterated that it is often the combined presence of these individual pathologies that gives rise to the patient that is totally refractory to treatment. In the absence of these pathologies, many horses with significant displacement of the distal phalanx are not in pain and are not in need of treatment. It thus follows that a key to the improved rehabilitation of difficult patients is focusing research on the physiopathology and diagnosis of these nonmechanical problems.

Gross and histopathological study of endotoxin-induced hoof lesions in cattle

In young cattle infusion of Escherichia coli endotoxin resulted in sole and wall haemorrhages that were more severe in the hind than in the fore feet. Histopathological examination of biopsies taken 5 days after infusion showed separation at the tips of the laminae, changes in the vascularity of the dermal papillae and laminae, lightly stained material in the sole horn and degeneration of the epidermal cells of the laminae and papillae. Later, densely stained material in the tubules of the sole, arteriosclerosis in all parts of the corium and proliferative changes in the laminae were seen. It is concluded that endotoxin can induce diffuse aseptic pododermatitis in cattle, characterized by initial degenerative changes in the papillae and laminae followed by proliferative changes in the laminae and arteriosclerosis in all parts of the corium.

“Subclinical” laminitis in dairy cattle

In dairying countries worldwide, the economic importance of lameness in cattle is now recognised. Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders such as white zone lesions, sole ulcer, and heel horn erosion. The existence of subclinical laminitis was first suggested in the late 1970s by Dutch workers describing the symptoms of sole haemorrhages and yellowish-coloured, soft sole horn. In an attempt to clarify some of the confusing and often conflicting terminology, the literature on laminitis is reviewed. Disturbed haemodynamics, in particular repeated or prolonged dilation of arteriovenous anastomoses, have been implicated in the pathogenesis of both equine and bovine laminitis. Some characteristics of the vascular system of the bovine claw which may be of importance in the pathophysiology of the subclinical laminitis syndrome are therefore discussed. Clinical observations suggest that subclinical laminitis is a multifactorial disease. The different factors that are or may be involved in its aetiology vary in complexity and severity according to the management protocol of the animals. The possible involvement of subclinical laminitis in claw lesions is assessed.

Possible importance for laminitis research of recent studies on substances influencing the differentiation of cultured keratinocytes

After a survey of the state of laminitis research the authors conclude that none of the present concepts of the pathogenesis of laminitis unequivocally explains the basic clinical and morphological observations in this disease. There is therefore reason to consider the advances that have been made during the last decades in respect to the influence of various substances on the differentiation of cultured skin keratinocytes. The technique is available for studying hoof keratinocytes in a comparable way. Relevant literature on cultured skin keratinocytes is surveyed. Some of the results from experimental studies on skin keratinocytes have an obvious connection with observations in laminitis, a fact which has led the authors to hypothesize that laminitis may be a "multifactorial" disease and that it may be provoked by agents stimulating multiplication of hoof keratinocytes with consequent reduction of differentiation.

Bovine laminitis: clinical aspects, pathology and pathogenesis with reference to acute equine laminitis

This review deals with the features of clinical and subclinical laminitis in cattle. Prominent clinical signs of acute laminitis are a tender gait and arched back. The sole horn reveals red and yellowish discolourations within five days. In subacute and chronic cases clinical signs are less severe. In chronic laminitis the shape of the claws is altered. Laminitis is frequently followed by sole ulceration and white zone lesions. Blood tests showed no significant changes for laminitic animals. Arteriographic studies of claws affected by laminitis indicated that blood vessels had narrowed lumens. Gross pathology revealed congestion of the corium and rotation of the distal phalanx. Histopathologic studies indicate that laminitis is associated with changes of the vasculature. Peripartum management and nutrition are important factors in its aetiology. It is hypothesised that laminitis is evoked by disturbed digital circulation. In the pathogenesis of acute laminitis three factors are considered important: the occurrence of thrombosis, haemodynamic aspects of the corium, and endotoxins which trigger these pathologic events.