Chronic interstitial pneumonia with features of organizing pneumonia in an adult horse

Miguel F. Carrillo, Deborah Kemper, Leslie W. Woods, Francisco R. Carvallo

Research output: Contribution to journalArticlepeer-review


A 22-y-old American Quarter Horse gelding was presented with a history of chronic progressive respiratory problems and a diffuse pulmonary nodular pattern in thoracic radiographs. The horse was euthanized, and 4 formalin-fixed samples of lung were submitted for histopathology. There were multifocal areas of marked thickening of alveolar septa as a result of proliferation of myofibroblasts embedded in fibromyxoid matrix (interpreted as “Masson bodies”), focal areas of fibrosis, and numerous papillary projections of connective tissue into bronchioles. A diagnosis of organizing pneumonia was reached. No etiology was found for this lesion. It is important to consider causes of chronic interstitial pneumonia with fibrosis in horses other than equid herpesvirus 5, such as complicated viral or bacterial pneumonia or chronic toxicoses.

Original languageEnglish (US)
Pages (from-to)621-625
Number of pages5
JournalJournal of Veterinary Diagnostic Investigation
Issue number4
StatePublished - Jul 1 2020


  • crofton weed
  • equid herpesvirus 5
  • horses
  • interstitial pneumonia

ASJC Scopus subject areas

  • veterinary(all)


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