Histologic Alterations of the Basement Membrane of the Dermal and Epidermal Layers of the Hoof in Horses With Acute Laminitis

Abstract

SUMMARY:The morphological characteristics of the hooves of two groups of horses were studied. The first group was comprised of six adult animals without any treatment and served as the control. The other group, comprised of seven horses, received carbohydrates overload orally. Of these, 71% developed laminitis between 36 and 48 hours after carbohydrate administration. After 48 hours of induction, the animals were sacrificed and their fore limbs and hindlimbs were removed for histologic study. Tissue sections 5 to 7 µm thick were obtained, stained with hematoxylin-eosin (H&E) or periodic acid Schiff's (PAS), and then examined by light microscopy. It was possible to identify in horses from the laminitis group, morphological and structural changes in the architecture of the primary and secondary epidermal lamellae, which were found to be sharpened and elongated with basal cells having round-shaped nuclei and also localized at the basal pole. PAS staining showed that in horses from the control group there were the presence of a basement membrane, separating and outlining the dermal and epidermal lamellae. In the laminitis group horses, there were deformation and fragmentation of the basement membrane. The utilization of PAS permitted the determination of the degenerative alterations in the basement membrane, which occurred early and coincident with the development of clinical signs of lameness.