Spectral analysis of respiratory noise in horses with upper airway disorders.
BACKGROUND
It has long been recognised that the production of abnormal respiratory sounds by horses during exercise is frequently associated with upper airway obstructions. Respiratory acoustic measurements have shown promise in investigation of upper airway disorders in man and, more recently, in horses with experimentally-induced obstructions.


OBJECTIVE
To evaluate sounds from exercising horses with naturally occurring dynamic obstructions of the upper respiratory tract and to compare these with those from normal horses in order to determine whether different obstructions produce characteristic spectral patterns.


METHODS
The audio signal, airflow and videoendoscopic images were recorded simultaneously during an incremental exercise test on a high-speed treadmill.


RESULTS
Spectral analysis of the audio signal showed marked differences between control and clinically afflicted horses. Dorsal displacement of the soft palate was characterised by a narrow low frequency (20-80 Hz) peak during expiration. Horses with dynamic laryngeal collapse produced inspiratory sounds characterised by a broad band high frequency spectral component in the range 1.1-2.7 kHz.


CONCLUSIONS
Spectral analysis of respiratory sounds in horses has potential as a diagnostic technique for field use especially when facilities for high-speed treadmill assessment are not practicable.
Franklin
S H
SH
Equine Sports Medicine Centre, Department of Anatomy, University of Bristol, Langford, Bristol BS40 5DU, UK.
Usmar
S G
SG
Lane
J G
JG
Shuttleworth
J
J
Burn
J F
JF
D000402:Airway Obstruction / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D003937:Diagnosis, Differential; D005080:Exercise Test / Q000662:veterinary; D006734:Horse Diseases / Q000175:diagnosis* / Q000503:physiopathology; D006736:Horses; D008297:Male; D010160:Palate, Soft / Q000473:pathology; D010805:Physical Conditioning, Animal / Q000502:physiology; D012135:Respiratory Sounds / Q000175:diagnosis / Q000502:physiology / Q000503:physiopathology / Q000662:veterinary*; D012140:Respiratory Tract Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D013057:Spectrum Analysis / Q000379:methods / Q000662:veterinary; D013637:Tape Recording; D014741:Video Recording