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

Abstract

Equine 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.