Abstracts: Equine sarcoids-causes, molecular changes, and clinicopathologic features: a review

Equine sarcoid is the most common skin tumour of horses. Clinically, it occurs as a locally invasive, fibroblastic, wart-like lesion of equine skin, which has 6 clinical classes: occult, verrucose, nodular, fibroblastic, mixed, and malignant. Sarcoids may be single but multiple lesions are more frequent.

The typical histological feature is increased density of dermal fibroblasts which form interlacing bundles and whorls within the dermis. Lesions are mostly persistent, resist therapy, and tend to recur following treatment. In general, sarcoids are not fatal but their location, size, and progression to the more aggressive form may lead to the withdrawal of a horse from use and serious infringement of their welfare leading to the loss of valuable animals.

Bovine papillomavirus (BPV) type 1 and less commonly type 2 contribute to the development of equine sarcoid. The viral genome and proteins are detected in a high percentage of cases. Furthermore, viral oncoprotein activity leads to changes in the fibroblastic tissue similar to changes seen in other types of tumors.

Equine sarcoids are characterized by a loss of tumour suppressor activity and changes allowing abnormal formation of the affected tissue, as well as y immune defense abnormalities that weaken the host’s immune response. This impaired immune response to BPV infection appears to be crucial for the development of lesions that do not spontaneously regress, as occurs in BPV-infected cows.

Keywords: bovine papillomavirus; horses; immunology; neoplasia; pathology; review; sarcoid; sarcoma; skin; virology.

Magdalena Ogłuszka 1Rafał Radosław Starzyński1Mariusz Pierzchała 1Iwona Otrocka-Domagała 2Andrzej Raś 2

Vet Pathol. 2021 May;58(3):472-482.doi: 10.1177/0300985820985114

1Institute of Genetics and Animal Biotechnology of the Polish Academy of Sciences, Jastrzębiec, Poland.

2University of Warmia and Mazury, Olsztyn, Poland.

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