The application of exhaled breath analysis in racing Thoroughbreds and influence of high intensity exercise on concentrations of nitric oxide and carbon monoxide 65 and pH in exhaled breath

Cathcart, M., Love, S., Sutton, D.G.M., Parkin, T.D.H. and Hughes, K.J. (2012) The application of exhaled breath analysis in racing Thoroughbreds and influence of high intensity exercise on concentrations of nitric oxide and carbon monoxide 65 and pH in exhaled breath. Journal of Veterinary Internal Medicine, 26(2), pp. 418-440. (doi:10.1111/j.1939-1676.2012.00912.x)

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Abstract

Purpose of the study: The analyses of exhaled breath (EB) andexhaled breath condensate (EBC) have been established as meth-ods for the diagnosis and monitoring of lung inflammatory dis-eases in human medicine. The application of non-invasivediagnostic techniques in the investigation of lower airway inflam-mation in horses holds much appeal. The aims of this study wereto (i) investigate whether both EB and EBC could be obtainedfrom Thoroughbred racehorses in the field setting, and (ii) inves-tigate the effects of exercise per se on the concentrations ofexhaled nitric oxide (NO) and carbon monoxide (CO) and EBCpH.Methods: EB and EBC were obtained from 23 Thoroughbredracehorses (median age 4 years, range 2-10) over a 5 day period,prior to and immediately following exercise. A single sample ofEB was collected for off-line measurement of NO and CO usinga chemiluminescence gas analyser (LR1800, Logan ResearchUK). EBC was collected by directing EB through a condensingchamber, chilled to -70ºC with dry ice. EBC samples were keptfrozen until time of analysis when, after defrosting, the pH of theneat EBC was measured using a bench top pH meter (pH21,Hanna Instruments Ltd). For each horse and sampling period,the ambient temperature and humidity, respiratory rate prior toand during sample collection were recorded. Paired data werecompared using a paired T-test and Wilcoxon signed-rank test,where appropriate. With outcome set as the difference betweenthe exhaled biomarkers before and after exercise, univariant andmultivariant general regression analysis was used to investigateany association between individual outcomes and the recordedvariables.Results: EB and EBC were collected successfully from allhorses before and after exercise with all horses tolerating the col-lection process. The volume of EBC collected was 1.4 ± 0.3mland 1.8 ± 0.4ml before and after exercise, respectively. ExhaledNO concentrations were above the detection limit of the analyser(1ppb) in only 8 of the 46 EB samples collected; NO was notincluded in further analysis. CO was measurable in all pre-exer-cise EB samples (median 1ppb, inter-quartile range 0.6-1.6ppb)and the concentration of exhaled CO decreased significantly afterexercise (median 0.4ppb, inter-quartile range 0.0-0.8ppb; p =0.005). Before exercise, pH of EBC was 4.52 ± 0.25 with a trendfor increased pH exercise (4.77 ± 0.60) which approached signifi-cance (p = 0.06). Horses housed in one specific barn were signifi-cantly more likely to have an increase in EBC pH post exercise(p = 0.005), suggesting an environmental or managemental influ-ence on this exhaled biomarker.Conclusions: This study is the first to document the successfulcollection of both EB and EBC from Thoroughbred racehorsesin a field setting. CO was detected in EB of all horses beforeexercise, which has not been recorded previously (Wyse et al2005). The cause of the significant decrease in CO after exerciseof the horses remains to be established, however enhanced alveo-lar diffusion capacity of CO, increases in airway volume, polyp-noea and alterations in haemoglobin affinity for CO may beinvolved. The trend toward increased EBC pH after exercise mayreflect alterations in concentrations of exhaled volatiles (e.g.ammonia) and deserves consideration in the application of thisbiomarker to the investigation of lower airway inflammation inhorses. Furthermore, the identification of a possible environmen-tal association with EBC pH is in agreement with results from aprevious study (Whittaker et al 2009) and the relationshipbetween environmental factors, pulmonary inflammation andEBC pH are worthy of further investigation.

Item Type:Articles
Additional Information:Proceedings of the 5th Congress of the European College of Equine Internal Medicine
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Love, Professor Sandy and Parkin, Professor Timothy and Hughes, Mr Kristopher and Sutton, Dr David
Authors: Cathcart, M., Love, S., Sutton, D.G.M., Parkin, T.D.H., and Hughes, K.J.
College/School:College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:Journal of Veterinary Internal Medicine
Publisher:American College of Veterinary Internal Medicine.
ISSN:0891-6640
ISSN (Online):1939-1676
Published Online:20 March 2012

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