Fibrose pulmonar multinodular dos equinos no sul do Rio Grande do Sul: patologia e diagnóstico diferencial

Abstract

This dissertation aimed to describe a case of equine multinodular pulmonary fibrosis (EMPF) diagnosed in the Laboratório Regional de Diagnóstico of Faculdade de Veterinária of Universidade Federal de Pelotas (LRD/UFPel) in a 15-year-old undefined breed equine. Clinical signs were characterized by respiratory distress, intermittent fever, anorexia, and dyspnea, with evolution of approximately 10 days. Macroscopically there was enlargement of the lungs with whitish, pale, firm and well delimited nodules, approximately 7-10 cm in diameter, distributed throughout the parenchyma. Histologically, lung nodules had alveolar spaces, with walls covered by cuboidal epithelium, containing macrophages, neutrophils, lymphocytes and hyperplasia of type II pneumocytes, and eventually multinucleated giant cells. The interstitium was markedly thickened by mature fibrous connective tissue and collagen. There were intranuclear inclusion bodies in macrophages. The PCR technique for detecting the EHV-5 DNA was positive. After confirming the diagnosis, a retrospective study of pneumonia cases with interstitial fibrosis diagnosed in horses in the LRD between 2000 and 2015 was performed. Two horses out of six diagnosed with pneumonia and interstitial fibrosis had macroscopic and histological lesions similar to those of EMPF, but they were negative in the PCR for the HVE-5.Four cases presented histological pattern incompatible with EMPF, ruling out the possibility of being the disease. This is the second report of this disease in Brazil, which was first described in 2007 in the United States. It is concluded that EMPF is a sporadic disease in southern Brazil, nevertheless it should be considered in cases of respiratory disease in horses. Reports of cases like this is important to alert veterinarians about the occurrence of diseases in Southern Brazil. It is also necessary to establish the real role of EHV-5 in the pathogenesis of the disease. Cases of pulmonary fibrosis like EMPF in which the virus is not present should be studied to establish whether it could be an idiopathic form of the disease.