Polo mare with weight loss and lung issues - what happened?

Abstract

CASE HISTORY: A 10-year-old polo mare presented with a history of weight loss, poor condition and inappetance. CLINICAL FINDINGS: The mare was tachycardic, tachypnoeic and febrile. Harsh lung sounds were auscultated over all lung fields. The mare initially responded to treatment with antibiotics, anti-inflammatory drugs and bronchodilators. Throughout the course of treatment, there was a variable lymphocytosis, monocytosis and fluctuation in concentrations of fibrinogen. The mare also developed a mild anaemia, most likely due to chronic disease. Despite treatment, the mare's condition deteriorated over the following 2 months, and she was subject to euthanasia. PATHOLOGICAL FINDINGS: On post mortem examination, white to pale tan, large coalescing fibrous nodules up to 5 cm in diameter were found distributed throughout the lungs. Histopathology revealed a multifocally severe interstitial pneumonia with superimposed bronchiolar or alveolar inflammation, fibrosis, Type II pneumocyte hyperplasia and histiocytic intranuclear inclusion bodies, consistent with the findings previously reported for cases of equine multinodular pulmonary fibrosis (EMPF). DIAGNOSIS: Equine multinodular pulmonary fibrosis based on characteristic gross and histopathological findings. The diagnosis was strengthened by detection of DNA for equine herpesvirus 5 in the lung tissue. CLINICAL RELEVANCE: This report describes the first recognised case of EMPF in New Zealand. The affected horse did not respond to treatment and was subject to euthanasia. The prognosis for horses with EMPF, based on a limited number of cases worldwide, is currently considered poor.