DISEASES OF THE RESPIRATORY ORGANS. 73 



oiher mucous surface in the body. 3. The extraordinary worn 

 to which the lungs are subjected in the rapid paces and severe 

 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 lungs directly, but on the 

 skin with which the lungs and all internal organs so closely 

 sympathise. 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. 6. 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 subjected, 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. 1 2. The arrest of circulation through the lungs owing 

 to imperfect aeration of the blood when an animal out of con- 

 dition is driven at a pace beyond his power of endurance. 



Modes of Physical Exploration of the Respiratory Orga?is. — 

 Auscultation ds^^ percussion are the most essential. The first is 

 the application of the ear alone or with a stethoscope to the 

 surface over some part of the respiratory organs (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 modifications followed on the diseased. In 

 general terms there is a blowing sound to be heard in liealth 

 over the nose, throat, windpipe, and between the upper and 

 middle thirds of the chest. In the rest of the chest is a soft, 

 rustling murmur, which has been compared to the gentlest 



