Infectious risk factors and clinical indicators for tracheal mucus in British National Hunt racehorses. (30th August 2013)

• Record Type: Journal Article
• Authors: Cardwell, J. M.; Smith, K. C.; Wood, J. L. N.; Newton, J. R.
• Is Part Of: Equine veterinary journal. Volume 46:Number 2(2014:Mar.)
• Page Start: 150
• Page End: 155
• Publication Date: 2013-08-30
• Subjects: Horses -- Diseases -- Periodicals; 636.108905
• DOI: 10.1111/evj.12109
• Languages: English
• ISSNs: 0425-1644

Abstract

<abstract abstract-type="main"> <title>Summary</title> <sec id="evj12109-sec-0001" sec-type="section"> <title>Reasons for performing study</title> <p>Many studies of respiratory disease in racehorses have focused on a combination of increased tracheal mucus and airway neutrophilia. Examination of each component separately should provide further insight into this condition.</p> </sec> <sec id="evj12109-sec-0002" sec-type="section"> <title>Objectives</title> <p>To identify infectious risk factors for endoscopically visible tracheal mucus in National Hunt racehorses.</p> </sec> <sec id="evj12109-sec-0003" sec-type="section"> <title>Study design</title> <p>A 2 year prospective longitudinal study.</p> </sec> <sec id="evj12109-sec-0004" sec-type="section"> <title>Methods</title> <p>Monthly quantitative bacteriological examinations of tracheal wash samples and viral serological examinations were conducted. Risk factors for 'small amounts of mucus' (mucus score = 1/3) and 'increased mucus' (score ≥2/3) were identified.</p> </sec> <sec id="evj12109-sec-0005" sec-type="section"> <title>Results</title> <p>There were increased odds of small amounts of mucus when both <italic>Streptococcus zooepidemicus</italic> and nonhaemolytic streptococci (NHS) were isolated (odds ratio [OR] 2.6; 95% confidence interval [CI] 1.5–4.6; P<0.001) but not when either species was isolated in the absence of the other. Increased odds of increased mucus were associated with the isolation of either <italic>S. zooepidemicus</italic> (OR 5.6; 95% CI 1.2–25.9; P = 0.03) or NHS (OR 3.7; 95% CI 1.2–11.6; P = 0.02), with an increased effect when both were isolated together (OR 12.5; 95% CI 3.7–41.6; P<0.001). Approximately 6‐fold increased odds of small amounts of mucus were associated with the first 3 months in training (OR 6.3; 95% CI 2.0–19.4; P<0.001) and 3‐fold increased odds of increased mucus associated with the first 6 months in training (OR 2.9; 95% CI 1.3–6.4; P = 0.01). Coughing at exercise and increased serous nasal discharge were specific but insensitive indicators of increased mucus.</p> </sec> <sec id="evj12109-sec-0006" sec-type="section"> <title>Conclusions</title> <p>Associations with <italic>S. zooepidemicus</italic> corroborate previous research, but an independent effect of NHS has not previously been reported. The possibility that there are individual pathogenic species within this group should be considered. Further work is required to identify <italic>S. zooepidemicus</italic> subtypes and NHS species associated with disease. Closer monitoring of the respiratory health of horses entering training for the first time is likely to be valuable.</p> </sec> </abstract>