Diseases of the Respiratory Organs. 165 



whicli the lungs are subjected in the rapid paces and se- 

 vere efforts made by the horse. 4. The close, impure air 

 of the stable in contrast to the clear bracing air of the fields 

 to which the colt has been accustomed. 5. The effect of 

 the hot relaxing air of the stable is not only on the limgs 

 directly but on the skin with which the lungs and all in- 

 ternal organs so closely sympathize. 6. The heats and 

 chills, and violent nervous excitement to which young 

 horses are subjected in passing into training and work. 



7. The changes of locality, feeding and management to 

 which young horses are subjected on leaving the breeder. 



8. The variable weather and sudden, extreme changes of 

 spring and autumn. 9. The susceptibility which results 

 from the want of habitude of bearing extreme heat and 

 cold, and which tells especially at the above seasons. 10. 

 The draughts of cold air to which animals are often sub- 

 jected, and particularly when warm and perspiring. 11. 

 The frequent exposure to cold drenching rains, night dews 

 and the like, after the excitement and relaxation consequent 

 on a hard day's work. 12. The arrest of circulation through 

 the lungs owing to imperfect aeration of the blood when an 

 animal out of condition is driven at a pace beyond his 

 power of endurance. 



Modes of Physical Exploration of the Bespiratory Organs. 

 Auscultation and percussion are the most essential. The 

 first is the application of the ear alone or with a stetho- 

 scope to the surface over some part of the respiratory or- 

 gans (nose, throat, windpipe, chest,) to listen to the natural 

 sounds of breathing and to detect any unnatural change 

 or absence of these sounds. The natural sounds must be 

 studied on the healthy animal, and then the different mod- 

 ifications followed on the diseased. In general terms there 

 is a blowing sound to be heard in health over the nose, 

 throat, windpipe, and between the upper and middle 

 thirds of the chest. In the rest of the chest is a soft, rus- 

 tling murmur which has been compared to the gentlest 

 eeohyr stirring dry leaves. Just behind the left elbow m 



