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Acta veterinaria Scandinavica2024; 66(1); 51; doi: 10.1186/s13028-024-00773-7

Clinical variability of equine asthma phenotypes and analysis of diagnostic steps in phenotype differentiation.

Abstract: Equine asthma is a common, non-infectious, chronic lung disease that affects up to 80% of the horse population. Strict phenotyping and identification of subclinically asthmatic horses can be challenging. The aim of this study was to describe equine asthma phenotypes (mild, moderate, and severe asthma) defined by BALF cytology and occurrence of clinical signs in a population of privately owned horses and to identify the variables and examination steps with best discriminative potential. The standardised examination protocol included clinical examinations, blood work, airway endoscopy with bronchoalveolar lavage fluid analysis, arterial blood gas analysis and radiography under clinical conditions performed by one veterinarian. Results: Out of 26 horses, four were diagnosed with mild (subclinical), seven with moderate, and seven with severe asthma based on clinical examination and BALF cytology. Eight horses served as controls. Cough with history of coughing was the strongest variable in phenotype differentiation. Factor analysis revealed an increasing clinical variability with disease severity and an overlapping of clinical presentations between phenotypes. Elevated mast cell (4/4 horses) and neutrophil counts (3/4 horses) in bronchoalveolar lavage cytology differentiated mild asthmatic horses from healthy horses. Moderate and severe asthmatic horses were characterised by clinical signs and neutrophil counts. Conclusions: The results indicate that medical history, clinical examination and bronchoalveolar lavage cytology are minimum indispensable steps to diagnose equine asthma and that phenotypes are clinically overlapping. A differentiation of three phenotypes without neutrophil and mast cell counts in bronchoalveolar lavage cytology is not sufficient for clinical diagnostics. A comparably exact diagnosis cannot be achieved by relying on alternative examinations used in this study. Screenings of inconspicuous horses with bronchoalveolar lavage can aid in diagnosing subclinically affected animals, however, group size was small, the procedure is invasive and clinical relevance of slightly elevated cells in bronchoalveolar lavage remains unclear. Clinical relevance could not be clarified in this study, since follow-up examinations or lung function testing were not performed.
© 2024. The Author(s).
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Publication Date: 2024-09-18 PubMed ID: 39294710PubMed Central: PMC11409572DOI: 10.1186/s13028-024-00773-7Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates the varying clinical manifestations of equine asthma and discusses the methods to differentiate the various severity levels of the disease. The study points out that reliance on clinical examinations, medical history and bronchoalveolar lavage cytology is essential for an accurate diagnosis due to the overlapping clinical displays among different phenotypes.

Research Objectives and Methodology

  • The study aimed to provide detailed descriptions of equine asthma phenotypes mainly mild, moderate, and severe, as defined by bronchoalveolar lavage fluid (BALF) cytology and the occurrence of clinical signs.
  • The study also intended to evaluate and identify variables as well as examination methods that offer the highest discriminative potential.
  • For the study, a standardized examination protocol was employed which included clinical examinations, airway endoscopy with bronchoalveolar lavage fluid analysis, arterial blood gas analysis, blood work, and radiography. A single veterinarian performed all procedures under clinical conditions.

Research Findings

  • The research covered a total of 26 horses, of which seven had moderate asthma, four had mild asthma, and seven had severe asthma. The degree of severity was based on BALF cytology and clinical examination. The rest of the horses served as controls.
  • The most significant variable in phenotype differentiation was a cough, specifically a medical history that indicated coughing.
  • The factor analysis demonstrated that the severity of the disease led to increased clinical variability and overlapping clinical presentations between phenotypes.
  • BALF cytology showing elevated mast cell and neutrophil counts distinguished mild asthmatic horses from healthy ones.
  • Clinical signs and neutrophil counts characterized moderate and severe asthmatic horses.

Conclusions

  • The findings show that an accurate diagnosis of equine asthma relies on medical history, clinical examination, and BALF cytology, given the fact that phenotypes display clinically overlapping signs.
  • The research concludes that differentiation of the three phenotypes solely based on neutrophil and mast cell counts in BALF cytology will not yield an accurate diagnosis.
  • Even though screenings of seemingly healthy horses with BALF can potentially identify subclinically affected horses, this procedure has its drawbacks because it is invasive, and the group size for this study was small. Moreover, the clinical significance of slightly elevated cell counts in BALF is yet to be identified.
  • The study could not clarify the clinical relevance of its findings as it did not include follow-up examinations or lung function testing.

Cite This Article

APA
Meiseberg LK, Delarocque J, de Buhr N, Ohnesorge B. (2024). Clinical variability of equine asthma phenotypes and analysis of diagnostic steps in phenotype differentiation. Acta Vet Scand, 66(1), 51. https://doi.org/10.1186/s13028-024-00773-7

Publication

Acta veterinaria Scandinavica
ISSN: 1751-0147
NlmUniqueID: 0370400
Country: England
Language: English
Volume: 66
Issue: 1
Pages: 51
PII: 51

Researcher Affiliations

Meiseberg, Lia Kristin
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany. Lia.Kristin.Meiseberg@tiho-hannover.de.
  • Institute of Biochemistry, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany. Lia.Kristin.Meiseberg@tiho-hannover.de.
Delarocque, Julien
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.
de Buhr, Nicole
  • Institute of Biochemistry, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.
  • Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Foundation, Bünteweg 17, 30559, Hannover, Germany.
Ohnesorge, Bernhard
  • Clinic for Horses, University of Veterinary Medicine Hannover, Foundation, Bünteweg 9, 30559, Hannover, Germany.

MeSH Terms

  • Horses
  • Animals
  • Asthma / veterinary
  • Asthma / diagnosis
  • Asthma / pathology
  • Horse Diseases / diagnosis
  • Horse Diseases / pathology
  • Phenotype
  • Bronchoalveolar Lavage Fluid / cytology
  • Female
  • Male

Conflict of Interest Statement

The authors declare that they have no competing interests.

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Citations

This article has been cited 2 times.
  1. Meiseberg LK, Mergani A, Delarocque J, Imker R, Köhn D, Wanes D, Bonilla MC, Veldhuizen EJA, von Köckritz-Blickwede M, Ohnesorge B, de Buhr N. Equine Asthma Is Characterised by Severity-Dependent Correlations Between Blood Neutrophil Cholesterol Content and NET Formation. Eur J Immunol 2025 Oct;55(10):e70072.
    doi: 10.1002/eji.70072pubmed: 41054022google scholar: lookup
  2. Röschmann J, Naef J, Doras C, Gerber V. Respiratory Rate Recovery After Submaximal Lunging Exercise Is Delayed in Asthmatic Horses with Neutrophilic Airway Inflammation. Animals (Basel) 2025 Mar 2;15(5).
    doi: 10.3390/ani15050713pubmed: 40075996google scholar: lookup
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