Respiratory Sounds recorded by Radio‐Stethoscope from Normal Horses at exercise

Abstract

SUMMARY A graphic representation is presented of respiratory sounds recorded by a radio‐stethoscope from normal horses exercised at the walk, trot, canter and gallop. Methods whereby inspiratory and expiratory sounds were distinguished are discussed. The form of amplitude envelopes of the sounds recorded at different gaits are compared. Certain measurements of relative amplitudes and the form of amplitude envelopes of the recorded respiratory sounds can be recognised as typical of normal horses when exercised at the canter and gallop. The influence of some physiological events (e.g. deglutition on the rhythm of normal respiration at the canter and gallop) is indicated. RÉSUMÉ On donne une représentation graphique des sons respiratoires recueillis sur le cheval normal à l'aide d'un radio stéthoscope au pas, au trot, au canter, au galop. Les méthodes permettant de différencier les sons inspiratoires et des sons expiratoires, sont discutées. On compare les résultats obtenus aux différentes allures. Certaines mesures des amplitudes relatives et la forme des amplitudes globales peuvent être considérées comme caractéristiques pour un cheval exercé au canter ou au galop. L'influence de facteurs physiologiques tels que la déglutition sur le rythme de la respiration normale, est envisagée. ZUSAMMENFASSUNG Die radio‐stethoskopisch aufgenommenen Atemgeräusche normaler Pferde im Schritt, Trab, langsamen und schnellen Galopp werden graphisch wiedergegeben. Die Methoden zur Unterscheidung exspiratorischer und inspiratorischer Geräusche werden besprochen. Die Amplitudenumrisse der Geräusche werden in verschiedenen Gangarten verglichen. Gewisse Messungen relativer Amplituden und die Form der Amplitudenumrisse der Atem geräusche können als typisch für das im Kanter oder schnellen Galopp arbeitende Pferd gelten. Physiologische Einflüsse, z.B. Abschlucken im Rhythmus der normalen Atmung im Kanter oder Galopp, werden diskutiert.

Time relationship between the respiratory cycle and limb cycle in the horse

“…Thus movement of the forelimbs during locomotion could be considered as the major factor influencing the timing of the respiratory cycle. The demonstrated phase relationship, at the canter and the gallop, can be changed by some physiological functions such as deglutition (Attenburrow 1978); by certain forms of exercises and by restraint, such as jumping, sprint galloping (Attenburrow 1978), bucking and control by lunge rein; and by coughing and diseases such as chronic obstructive pulmonary disease.…”

“…Atypical phase relationship between the respiratory and limb cycles was most obvious during experiments to record the respiratory sounds generated by untrained yearling Thoroughbreds exercised on a lunge rein. Methods other than subjective observation of limb movement for detecting the expiratory period require to be developed before useful comparisons (Attenburrow 1978) can be made between maximum amplitudes of inspiratory and expiratory sounds generated by yearlings exercised and restrained by lunge rein.…”

“…Harnicke and Meixner (1977) concluded that respiration and stride frequency were completely synchronised during galloping. Attenburrow (1976;1978) recorded amplitude envelopes for respiratory sounds that were characteristic for the canter and gallop, but which varied considerably at the walk and trot. This author concluded that the shape of amplitude envelopes and phase relationships recorded at all gaits suggested that the rhythm of respiration and, therefore, respiratory sound generation could be influenced by limb movement.…”

Impedance plethysmography

“…The changes in impedance shown in Figure 7, when compared subjectively with the characteristic amplitude envelope of the respiratory sounds at the canter (Attenburrow 1978b), show that inspiration corresponds to a rising impedance trace (increasing lung volume) and expiration to a falling trace. In Figure 8, the plethysmograph trace represents the differentiated signal indicated in Figure 7 and shows that rate of change of lung volume (flow rate) at peak expiratory and inspiratory flow indicated by plethysmography occurs at the same instant as peak amplitude values of the recorded respiratory sound.…”

A comparison of techniques to enhance the evaluation of equine laryngeal function

“…The clinical sign of inspiratory dyspnoea results from an inability to abduct the left arytenoid cartilage and vocal cord. The criteria used to diagnose ILH include inspiratory noise (roaring, whistling), exercise intolerance, palpable atrophy of the left cricoarytenoideus dorsalis muscle, a positive arytenoid depression test and endoscopic evidence of left arytenoid dysfunction (Cook 1965;Cook 1988;Marks, Mackay-Smith, Cushing and Leslie 1970;Attenburrow 1978Attenburrow , 1983Haynes 1986;Lane 1987). The use of the endoscope in examination of the equine upper respiratory tract was documented by Cook (1974) and was reviewed by Lane (1987).…”