sarcoidosis in horse with clinical and histopathological description of three cases

Sarcoids are the most common skin tumor of horses. they affect breeds of all ages and both sexes. sarcoids have a range of appearances and behaviours. there are six gross morphological types: verrucous, fibroblastic, nodular, mixed, malignant, and flat. sometimes skin lumps become ulcerated and predispose the occurrence of some other diseases. habronemiasis is a parasitic disease caused by habronema and draschia. this disease is transmitted through flies that feed on the skin ulcers, leading to the deposition of the larvae. inappropriate treatments can make sarcoid more aggressive, in particular in situations when the treatment fails and causes the sarcoid to grows back. the aim of this report is a clinical description of three horses suffering from sarcoidosis. between 2016 - 2024 three horses with cutaneous lesions were referred to the veterinary hospital of shahid chamran university of ahvaz. they were 8 to 12 years old. they referred due to cutaneous lesions. after clinical examination, surgery was performed in two horses and samples were sent for histopathological study. in one horse, the histopathological study revealed a dense proliferation of spindle cells and the eosinophilic bundles arranged in whorls and herringbone patterns. also, epithelial pegs were extending into dermis. in two horses, in addition to proliferated spindle cells, diffuse accumulation of eosinophils was observed around necrotic eosinophilic parts. two horses were cured and after one year they had no reoccurrence but in one horse treatment did not happen and the animal died. according to microscopic results sarcoidosis were diagnosed and in two horses it was concurrent with habronemiasis. appropriate several samplings is proposed because it helps to have a complete view of the entire lesion. sometimes incorrect sampling may cause misdiagnosis.