502 AUSCULTATION. 



their stages, and with the most surprising accuracy, by 

 the physician. With us it is far otherwise. The great 

 and muscular shoulder placed on each side of the chest 

 anteriorly, virtually prevents examination of the front por- 

 tions of the lungs, especially in the horse. The great 

 muscular masses lodged on each side of the vertebral 

 column, interfere in a similar way with the examination 

 of the superior portions of these organs. The false ribs are 

 in their turn covered by a considerable thickness of muscle, 

 which hinders the exploration of this region, and the whole 

 is covered by a thick cutaneous muscle, which not only tends 

 to deaden sound, but the movements of which, especially in 

 summer, corrugate the skin, and sometimes greatly interfere 

 with our investigation. Add to these the horizontal posi- 

 tion of the body, the oblique arrangement of the dia- 

 phragm, and the consequent pressure of the digestive organs 

 far into the thoracic cavity, and it will readily be understood 

 why we gain less favourable results from these physical 

 methods of examination than does the medical man. 



The nasal chambers, the larynx and trachea, are super- 

 ficially seated and readily accessible to physical methods of 

 diagnosis in all our domestic animals. The extent of the 

 thoracic walls, however, which yield instructive indications on 

 the application of these tests, varies with the species, and in 

 order to their correct application, a knowledge of such dif- 

 ferences is essential. 



Horse. The heavy muscular shoulder of the horse covers 

 the anterior part of the thorax as far back as the sixth rib in 

 ordinary circumstances. By raising and advancing the limb, 

 however, the cavity may be explored to the fifth, and in some 

 cases, as far as the fourth rib. The diaphragm, it must be 

 borne in mind, is attached on the ends of the false ribs, and 

 in the case of the posterior ribs, at a gradually increasing 



