Abstract: 【Objective】 This study was aimed to investigate the lameness of horses in some areas of Yili,Xinjiang,and explore the imaging findings and histopathological features of laminitis in natural clinical cases,so as to provide reference for further elucidating the pathogenic mechanism of laminitis.【Method】 Through clinical examination and lameness grade evaluation,the lameness of 655 horses in part of Yili,Xinjiang was investigated,and imaging diagnosis was made for horses with limb and hoof disease.At the same time,the lamellar tissues of 3 horses with laminitis were collected to make pathological sections,and the histopathological features were observed by hematoxylin-eosin (HE) and periodic acid Schiff (PAS) staining.【Result】 A total of 103 horses in this area showed clinical lameness,and the proportions of lameness≥grade 3 in small,medium,and large scale farms were 10.9%,14.4% and 17.2%,respectively.Imaging differential diagnosis showed that lameness horses had different degrees of arthritis,laminitis and flexor tendinitis.X-ray imaging showed that the third hoof bone remodeled,the dorsal hoof distance widened,the dorsal hoof bone was not parallel to the dorsal hoof wall,the ratio between the measured dorsal hoof distance and the lateral volar length of the road bone was greater than 30%,and the crown extension distance increased.HE staining result showed that the epidermal lamellar and dermal lamellar were loosely connected,the tip of the epidermal lamellar was sharp,the primary epidermal layer was edema to varying degrees,the secondary epidermal lobules were scattered,and there were a large number of hemosiderin-containing and fibroblasts scattered in some areas of the dermal lamellar,and occasionally a small number of eosinophils.PAS staining result showed that the basal membrane and epidermal basal cells were separated to varying degrees,the boundary between epidermis and dermis was blurred,there was no clear boundary of the basal membrane,the number of secondary basal cells increased and their distribution was chaotic,but the hoof layer of the secondary epidermis was shortened,the tip became blunt and the nucleus was elongated.【Conclusion】 The lameness of horses in some areas of Yili,Xinjiang showed an increasing trend with the increase of the scale of horse farms.Common limb and hoof diseases were the main causes of lameness.The imaging findings of some clinical cases of natural laminitis were consistent with the criteria of chronic laminitis,and the histopathology showed that it had developed to a chronic irreversible stage.Imaging and histopathological features could correlate apparent imaging changes and microscopic epidermal changes with the severity of clinical lameness,which could provide theoretical basis for the diagnosis of chronic laminitis.

Key words: horse; limb and foot disease; laminitis; imaging; histopathology