A case series highlighting the role of different gamma-herpesviruses in Equine Multinodular Pulmonary Fibrosis.

INTRODUCTION: This case series describes three cases of equine multinodular pulmonary fibrosis (EMPF) diagnosed at the Clinic for Equine Internal Medicine at the University of Zurich between 2012 and 2017. Current information on etiology and treatment options are presented. Two horses showed mild signs of chronic lower respiratory tract disease and one horse was presented with acute signs of disease including recurrent fever spikes and tachypnea. Diagnosis was achieved by physical examination, radiographic findings, and PCR testing for equine herpesviruses (EHV) of bronchoalveolar lavage (BAL) fluid or lung tissue obtained by biopsy. All horses were euthanized due to continuing deterioration after attempted treatment. Post mortem histological examination of lung tissue showed severe multifocal diffuse to confluent fibrosis in two cases and in another horse a discrete nodular fibrosis pattern. Panherpes nested PCR revealed the presence of equine herpesvirus 5 (EHV-5) DNA in lung tissue of one horse whereas in two other horses, asinine herpes virus 5 (AHV-5) was detected. EMPF should be considered as a differential diagnosis in horses with acute and chronic respiratory disease, including horses non-responsive to treatment for equine asthma.

INTRODUCTION: Cette série de cas décrit trois cas de fibrose pulmonaire multinodulaire équine (EMPF) diagnostiqués à la Clinique de médecine interne équine de l'Université de Zurich entre 2012 et 2017. Des informations actuelles sur l'étiologie et les options de traitement sont présentées. Deux chevaux présentaient de légers signes de maladie chronique des voies respiratoires inférieures et un cheval présentait des signes aigus de maladie, notamment des pics de fièvre récurrents et une tachypnée. Le diagnostic a été obtenu grâce à un examen physique, des résultats radiographiques et des tests PCR pour les virus herpès équins (EHV) du liquide de lavage broncho-alvéolaire (BAL) ou du tissu pulmonaire obtenus par biopsie. Tous les chevaux ont été euthanasiés en raison d'une détérioration continue après une tentative de traitement. L'examen histologique post mortem du tissu pulmonaire a montré une fibrose multifocale diffuse à confluente sévère dans deux cas et chez un cheval un type de fibrose nodulaire discret. La PCR par Panherpes a révélé la présence d'ADN de virus herpès équin 5 (EHV-5) dans le tissu pulmonaire d>un cheval alors que chez deux autres chevaux, le virus de l>herpès asinien 5 (AHV-5) a été détecté. L'EMPF doit être considéré comme un diagnostic différentiel chez les chevaux souffrant d'une maladie respiratoire aiguë et chronique, y compris les chevaux ne répondant pas au traitement de l'asthme équin.

Equine multinodular pulmonary fibrosis in southern Brazil: pathology and differential diagnosis / Fibrose pulmonar multinodular em equinos no Sul do Rio Grande do Sul: patologia e diagnóstico diferencial

Equine multinodular pulmonary fibrosis (EMPF) diagnosed at the Laboratório Regional de Diagnóstico of Faculdade de Medicina Veterinária, Universidade Federal de Pelotas (LRD/UFPel), is described. Differential aspects of other pulmonary diseases in horses with pneumonia and interstitial fibrosis were discussed. The disease occurred in a 15-year-old equine that presented with clinical signs of respiratory distress, intermittent fever, anorexia, and dyspnea. 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, the lung nodules had alveolar spaces with walls covered by cuboidal epithelium containing macrophages, neutrophils, lymphocytes, 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 the macrophages. The PCR technique for detecting the EHV-5 DNA was positive. In a retrospective study of pneumonia cases in horses with interstitial fibrosis diagnosed in the LRD/UFPel, two animals had macroscopic and histological lesions similar to those with EMPF, but they were negative for EHV-5 in PCR. Four cases diagnosed with pneumonia and interstitial tissue fibrosis had a histological pattern that was different from that observed in the EMPF animal, thus eliminating the possibility of EMPF. It is concluded that EMPF is a sporadic disease that should be considered in cases of respiratory disease in horses. Reports of such cases are important to alert technicians about the occurrence of rare diseases in Brazil. It is also necessary to establish the true role of EHV-5 in the pathogenesis of EMPF. Cases of pulmonary fibrosis such as EMPF, in which the virus is not present, should be studied to establish whether it could be an idiopathic form of the disease.(AU)

Descreve-se a fibrose multinodular pulmonar equina (EMPF) diagnosticado no Laboratório Regional de Diagnóstico da Faculdade de Veterinária da Universidade Federal de Pelotas. Foram discutidos a patologia da doença e os aspectos diferenciais de outras enfermidades pulmonares de equinos que cursam com pneumonia e fibrose intersticial. A doença ocorreu em um equino sem raça definida de 15 anos de idade que apresentou sinais clínicos de dificuldade respiratória febre intermitente, anorexia e dispneia, com evolução de aproximadamente 10 dias. Macroscopicamente havia aumento de volume dos pulmões e nódulos esbranquiçados, pálidos, firmes e bem delimitados, de aproximadamente 7-10 cm de diâmetro, distribuídos pelo parênquima. Histologicamente, o tecido pulmonar apresentava nódulos caracterizados pela presença de espaços alveolares, com paredes revestidas por epitélio cuboidal achatado, contendo macrófagos e neutrófilos e havia, também, linfócitos e hiperplasia de pneumócitos tipo II e eventualmente células gigantes multinuacleadas. O interstício estava acentuadamente espessado por tecido conjuntivo fibroso maduro e por colágeno. Havia corpúsculos de inclusão intranucleares em macrófagos. A técnica de PCR para detecção do DNA de herpes vírus equino-5 (EHV-5) resultou positiva. Em um estudo retrospectivo de casos de pneumonia com fibrose intersticial diagnosticados no LRD entre 2000 e 2015, dois equinos apresentaram lesões macroscópicas e histológicas similares às de EMPF, porém resultaram negativos na PCR para detecção de EHV-5. Quatro casos de pneumonia com fibrose do tecido intersticial apresentaram padrão histológico diverso da EMPF descartando-se a possibilidade de tratar-se da doença. Conclui-se que EMPF é uma enfermidade esporádica, no entanto deve ser levada em consideração em casos de doença respiratória em equinos. A descrição dos casos diagnosticados é importante para alertar técnicos sobre a ocorrência da mesma no Brasil. É necessário estabelecer o real papel do EHV-5 na patogenia da doença. Casos de fibrose pulmonar semelhantes à EMPF em que não esteja presente o vírus, devem ser estudados a fim de ficar estabelecido se poderia ser uma forma idiopática da mesma doença.(AU)