Scanning Electron and Light Microscopic Observations on the Hoof in Equine Laminitis

Abstract

The authors studied three horses with equine laminitis that had an affected hoof on the front right side and an unaffected hoof on the back right side which were diagnosed by X-ray examination. Three other horses with 6 unaffected hooves on the front and back left side were also studied as a control by scanning electron and light microscopy.
The findings of the affected hooves are as follows: The coconformations of cornual tubuli (tubuli epidermales) and dermal papillae (papillae dermales) in the cornu (corona) were irregular in pattern. The interface between the dermal lamina (lamellae dermales) and epidermal lamina (lamellae epidermales) in the middle paries and apex ungulae was irregular. The epidermal lamina was complicated in structure with varied lengths and the internal corneum (stratum internum) became thicker. The delineate of the secondary epidermal lamina was unclear, and the onychogenic fibrils were hypoplastic. The structural patterns of the cornual tubuli in the sole (soles) and the interface at the white line (zona alba) between the cornual paries and the sole in the epidermal lamina had irregular faces. However, the interface between the cornual tubuli and the toric dermis (dermis tori) in the toricungula (torus ungulae) were not changed.
The dermis contained a dilated venous and edematous arterial wall. In the spinous layer of the epidermis, thickening due to progressive proliferation and edematous degeneration were found. The cells of the spinous layer had abundant keratohyalin granules in their cytoplasm.