Chronic interstitial pneumonia with features of organizing pneumonia in an adult horse.
Abstract: 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.
Publication Date: 2020-07-21 PubMed ID: 32687009PubMed Central: PMC7438643DOI: 10.1177/1040638720936251Google Scholar: Lookup
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Summary
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The research article discusses a case of a 22-year-old American Quarter Horse that suffered from chronic progressive respiratory problems, which were ultimately diagnosed as organizing pneumonia, a rare condition.
Case Presentation
- The subject of the study was an American Quarter Horse gelding, aged 22 years, which had been experiencing chronic progressive respiratory issues. These problems were severe enough that they appeared as a diffuse pulmonary nodular pattern in the horse’s thoracic radiographs – a set of X-ray images of its chest.
- Due to its health issues, the horse was eventually euthanized. For further investigation of the root cause of the horse’s respiratory problems, 4 formalin-fixed samples of the horse’s lung were submitted for histopathology – the study of changes in tissues caused by disease.
Findings and Diagnosis
- The findings from the histopathology presented several abnormalities in the lung tissues of the horse. These abnormalities included multifocal areas where the walls separating the alveoli (air sacs in the lung) were markedly thickened due to the proliferation of myofibroblasts – a type of cell that plays a crucial role in wound healing and the replacement of normal tissue with fibrous tissue (scar tissue).
- These myofibroblasts were embedded in a fibromyxoid matrix – a soft, gelatinous tissue – resulting in structures interpreted as “Masson bodies”, a characteristic formation in certain types of lung diseases.
- The lung samples also displayed focal areas of fibrosis – the thickening and scarring of connective tissue – along with numerous papillary projections of connective tissue protruding into bronchioles, the small airways in the lungs.
- All these findings led researchers to diagnose the horse’s condition as organizing pneumonia, a rare and specific form of pneumonia characterized by the presence of fibrous plugs in the airspaces and bronchioles.
Implications
- Despite the detailed investigation, researchers were unable to identify the cause of the horse’s organizing pneumonia. They highlight that although equid herpesvirus 5 is often implicated in cases of chronic interstitial pneumonia with fibrosis in horses, other causes such as complicated viral or bacterial pneumonia or chronic toxicoses should be considered.
- The study emphasizes the significance of comprehensive diagnostic investigation in horses presenting with chronic respiratory conditions to ensure accurate diagnosis and appropriate treatment strategies.
Cite This Article
APA
Carrillo MF, Kemper D, Woods LW, Carvallo FR.
(2020).
Chronic interstitial pneumonia with features of organizing pneumonia in an adult horse.
J Vet Diagn Invest, 32(4), 621-625.
https://doi.org/10.1177/1040638720936251 Publication
Researcher Affiliations
- Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela, Colonia, Uruguay (Carrillo).
- West Coast Equine Hospital, Somis, CA (Kemper).
- California Animal Health and Food Safety Laboratory, University of California-Davis, Davis, CA (Woods).
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA (Carvallo).
- Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela, Colonia, Uruguay (Carrillo).
- West Coast Equine Hospital, Somis, CA (Kemper).
- California Animal Health and Food Safety Laboratory, University of California-Davis, Davis, CA (Woods).
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA (Carvallo).
- Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela, Colonia, Uruguay (Carrillo).
- West Coast Equine Hospital, Somis, CA (Kemper).
- California Animal Health and Food Safety Laboratory, University of California-Davis, Davis, CA (Woods).
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA (Carvallo).
- Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela, Colonia, Uruguay (Carrillo).
- West Coast Equine Hospital, Somis, CA (Kemper).
- California Animal Health and Food Safety Laboratory, University of California-Davis, Davis, CA (Woods).
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA (Carvallo).
MeSH Terms
- Animals
- Fatal Outcome
- Horse Diseases / diagnosis
- Horse Diseases / etiology
- Horse Diseases / pathology
- Horses
- Lung / pathology
- Lung Diseases, Interstitial / diagnosis
- Lung Diseases, Interstitial / etiology
- Lung Diseases, Interstitial / pathology
- Lung Diseases, Interstitial / veterinary
- Male
- Pneumonia / diagnosis
- Pneumonia / etiology
- Pneumonia / pathology
- Pneumonia / veterinary
Conflict of Interest Statement
Declaration of conflicting interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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Citations
This article has been cited 1 times.- Rahman A, Uzal FA, Hassebroek AM, Carvallo FR. Retrospective study of pneumonia in non-racing horses in California. J Vet Diagn Invest 2022 Jul;34(4):587-593.
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