Sarcoide equino no sul do Rio Grande do Sul: casuística de 20 anos

Abstract

The goal of this dissertation was study the epidemiology and distribution of equine sarcoid lesions received at the Laboratório Regional de Diagnóstico da Faculdade de veterinária da Universidade Federal de Pelotas (LRD/UFPel) in a period of 20 years. The main types of sarcoid were also determined and, by the PCR technique, the type of bovine papillomavirus (BPV) involved in the lesions of horses in the region were identified. The equine sarcoid cases received in the period from 2000 to 2020 were rescued by reviewing the LRD/UFPel necropsy protocols. The paraffin blocks of each case were cut into 3-5µm thick sections, stained using the hematoxylin and eosin (HE) technique. The macroscopic characteristics described in the protocols associated with histopathology allowed the determination of the type of sarcoid in each case. The samples sent to the LRD/UFPel in 2021 were divided, with a part fixed in 10% buffered formalin for histopathology and immunohistochemistry (IHC) and another part sent frozen to the Laboratório de Virologia e imunologia da universidade Federal de Pelotas (LabVir/UFPel), to identify the presence of BPVs through the molecular technique of PCR. In the period studied, 258 cases of sarcoid were diagnosed, representing 41.95% of cases of skin lesions in horses. Of these, 75.96% occurred in Crioulo horses. Horses aged between two and five years (42.64%) were the most affected. In 46.8% of the cases, the sarcoids were of the fibroblastic type. Of the 258 cases, 61% were single and in 32% of the cases the lesions were multiple. The IHC was negative for protein S-100 and positive for vimentin. The present paper showed that in the southern region of Rio Grande do Sul, equine sarcoid is the most important equine skin neoplasm. It was observed that the disease occurs mainly in animals of the Crioulo breed, which is the most numerous in the region and that horses aged 24 months to five years are among the most frequently affected. Single lesions are the most numerous and occur on the limbs.It was possible to suggest that sarcoid lesions smaller than 7.5 cm are more likely to not recur after complete excision. The most frequently diagnosed type is fibroblastic. The BPV genome was not detected by PCR in the analyzed samples. These results demonstrate that conventional diagnostic techniques may be underestimating the genetic diversity of this viral family. In the present study, the degenerate primers FAP59/64 (widely used in the scientific literature) were used, but with inherent limitations due to the genetic diversity of BPV.