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Frontiers in veterinary science2019; 6; 74; doi: 10.3389/fvets.2019.00074

Bronchoalveolar Lavage Cytology Characteristics and Seasonal Changes in a Herd of Pastured Teaching Horses.

Abstract: Equine asthma syndrome (EAS) is a common problem that affects horses of any age. Severe EAS is reported to affect 10-20% of adult horses in the northern hemisphere, while mild/moderate EAS is reported to affect 60-100% of adult horses, depending on the population and geographic region. For both severe and mild/moderate EAS, the presence of lower airway inflammation is attributed to airborne "triggers" such as dust, mold, and bacterial components that horses encounter in hay and stable-environments; and treatment recommendations for horses with EAS often include full-time pasture turnout. The caveat to this recommendation is horses with summer-pasture associated EAS (SP-EAS), who experience allergic lower airway inflammation when exposed to summer pasture. The prevalence of EAS in horses on pasture that do not have SP-EAS has not been reported. The purpose of this study was to use bronchoalveolar lavage (BAL) cytology to determine the prevalence of EAS in a herd of pastured, adult research horses with no history of respiratory disease. The horses were members of a teaching animal herd housed on pasture in the southeastern United States and fed round-bale Bermuda-grass hay. BAL fluid (BALF) cytology was analyzed in both summer (May-August 2017) and winter (November 2017-February 2018). Similar to previous reports, the prevalence of severe EAS in our study population was 10% in summer and 4.3% in winter. The prevalence of mild/moderate EAS was 60% in summer and 87% in winter. The high prevalence of mild/moderate EAS in this population was unexpected, given the 24-h, year-round pasture environment and the lack of history of respiratory disease. Additionally, 61.1% of horses with both summer and winter data had a different BALF cytology profile between the two seasons. To the authors' knowledge, this is the first study to use BAL cytology to diagnose, and monitor changes in, EAS phenotype in pastured adult horses. These results help to inform discussions regarding prevalence of EAS in pastured, adult horses in the southeastern region of North America.
Publication Date: 2019-03-14 PubMed ID: 30923711PubMed Central: PMC6426765DOI: 10.3389/fvets.2019.00074Google 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.

The study focused on examining the prevalence of Equine Asthma Syndrome (EAS) in a group of pastured adult research horses with no prior history of the disease. Using bronchoalveolar lavage cytology, they tracked the changes in EAS in different seasons. They found the prevalence of EAS to be high, irrespective of the season, contrasting the general perception of a reduced EAS prevalence due to the absence of respiratory disease history and the horses’ constant pasture-based environment.

Introduction

  • This research explores the prevalence of Equine Asthma Syndrome (EAS) in horses that are situated in a pasture environment most of the time.
  • EAS affects many horses, perhaps 10-20% of all adults in severe cases, and up to all adult horses in some mild or moderate cases, and is triggered predominantly by presence of lower airway inflammation caused by exposure to airborne allergens such as dust, mold, and bacterial components predominantly found in hay and stables.
  • Typically, horses showing symptoms of EAS are recommended to be placed in pastures full-time to alleviate their symptoms. In some cases however, horses experience similar allergic inflammation while pasturing.

Methodology

  • This study used bronchoalveolar lavage (BAL) cytology to determine the prevalence of EAS in the herd of research horses.
  • The horses were part of a teaching herd, kept in pastures in southeastern United States, and were fed with Bermuda-grass hay.
  • The BAL fluid (BALF) cytology was analyzed in two different seasons, summer (May-August 2017) and winter (November 2017-February 2018).

Results

  • The study reported a 10% prevalence of severe EAS in summer and 4.3% in winter.
  • The prevalence for mild/moderate EAS was 60% in summer, increasing to 87% in winter.
  • Most surprisingly though was the observation that over 61% of horses exhibited different BALF cytology profiles over the two seasons.

Conclusion

  • This was the first study of its kind to use BAL cytology to diagnose and monitor changes in EAS phenotype in pastured adult horses.
  • The results challenge conventional wisdom regarding prevalence of EAS in pasture-dwelling adult horses, as the prevalence reported was unexpectedly high despite the horses being in a 24h/year-round pasture-based environment and having no record of previous respiratory disease.
  • The findings of this study can help inform discussions regarding prevalence of EAS in pastured, adult horses in the southeastern region of North America.

Cite This Article

APA
Davis KU, Sheats MK. (2019). Bronchoalveolar Lavage Cytology Characteristics and Seasonal Changes in a Herd of Pastured Teaching Horses. Front Vet Sci, 6, 74. https://doi.org/10.3389/fvets.2019.00074

Publication

ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 6
Pages: 74
PII: 74

Researcher Affiliations

Davis, Kaori Uchiumi
  • Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States.
  • Comparative Medicine Institute, North Carolina State University, Raleigh, NC, United States.
Sheats, Mary Katherine
  • Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States.
  • Comparative Medicine Institute, North Carolina State University, Raleigh, NC, United States.

Grant Funding

  • T32 OD011130 / NIH HHS

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