98 CLINICAL DIAGNOSTICS. 



The inspiratory dyspnea. If the entrance of 

 air into the respiratory organs is made difficult, the animal 

 seeks to overcome the condition by taking forced inspirations. 

 N o t o n 1 y i s t h e d i a p h r a g m a c t i V e 1 y e m p 1 o >' e d, 



b u t o t h e r m u s c 1 e s w h i c h a r e n o r m a 1 1 \- n o t u s e d 

 during inspiration are called into play. 

 These muscles are: the serratus magnus, serratus anticus,. 

 external intercostals, levatores, costarum, scalenus. The 

 following clinical s }• m p t o m s character- 

 ize dyspnea: 



The nostrils are widely distended; dogs, fowls, cattle and 

 swine breathe with their mouths open. Dogs sometimes close 

 the jaws and breathe through the lateral commissures of the 

 mouth, sucking in the cheek at each inspiration. The head 

 and neck are extended horizontally, the larynx is retraced, the 

 ribs greatly elevated and rolled forward. The forelimbs are 

 spread far apart and the elbows turned out so that the serrati 

 and pectoral muscles can better come into play. 



If, in aggravated inspiratory dyspnea, the air enters the- 

 lung very slowly, notwithstanding that the ribs are greatly 

 elevated, and the thorax is distended to a degree which does 

 not correspond to the quantity of air passing in, a suction 

 pressure will occur, which can be recognized by a sinking of 

 the lozvcr anterior thoracic zvall — particularly of its inter- 

 costal spaces. 



Inspiratory dyspnea is observed: 



1. In a pure form in bilateral paralysis (paraplegia) of 

 the larynx and in severe cases of unilateral paralysis of the 

 organ (hemiplegia, roaring). It is characterized by the above 

 cited inspiratory dyspnea and the appearance of a stenotic 

 laryngeal bruit. In less severe cases of roaring this symp- 

 tom can only be brought out by exercising the patient. The- 

 act of expiration is performed without difficulty. 



2. In less pure form where a stenosis of the nasal pas- 



