Equine multinodular pulmonary fibrosis and presumed corticosteroid‐induced side effects in a horse

Abstract

SummaryEquine multinodular pulmonary fibrosis (EMPF) associated with herpesvirus‐5 infection (EHV‐5), is a severe, fibrosing interstitial lung disease of horses. Most common reported clinical signs are pyrexia, weight loss, depression, respiratory distress with tachypnoea and cough. Multiple tissue tropism of the EHV‐5 has been suggested. Treatment with valacyclovir and corticosteroids has been reported to be successful in a few cases, but the disease is usually associated with a poor prognosis because of progressive impairment of respiratory function. Corticosteroid administration can carry potential side effects, such as hypothalamic–pituitary–adrenal axis suppression, laminitis and increased susceptibility to infections. This report described a case of an 11‐year‐old gelding diagnosed with EMPF. The horse was treated with valacyclovir and corticosteroids and, after a transient initial improvement, showed a rapid deterioration of clinical signs and multiple complications, including severe bacterial dermatitis, liver damage and pleural effusion of unknown origin. A polymerase chain reaction (PCR) assay of liver biopsy sample was positive for EHV‐5, confirming the virus' multiple tissue tropism. A role of corticosteroids in exacerbating the disease progression and the increasing susceptibility to infections was strongly suspected.