RESPIRATORY APPARATUS. 93 



of respiration. The value of these changes to diagnostics is 

 limited. 



The intensity (depth) of the respirations is not marked 

 in healthy animals standing at rest. The alae of the nostrils 

 are hardly moved, and the ribs but slightly raised. The 

 intensity is i n c r e a s e d by exercise ; if it is augmented 

 and the animal at rest, it denotes disease. Horses dilate the 

 nostrils trumpet-like, dogs open the mouth (pant) and pro- 

 trude the tongue. The movements of the ribs and flanks are 

 pronounced. The development of the intensity agrees with 

 the degree of dyspnea. 



The intensity is diminished when the pleura, 

 chest wall or diaphragm is diseased. 



The intensity can become asymmetrical 

 in that one side of the thorax undergoes a deeper or more 

 rapid movement than the other side. This is seen in painful 

 unilateral pneumonias or pleurites. 



Wlien the rhythm and intensity of breathing is normal 

 and the ribs and abdomen are moved with even regularity, the 

 type of the respirations is spoken of as costo-ahdominal. 

 If the respiratory movements are produced principally by the 

 auxiliary muscles of breathing, which dilate the thorax, the 

 type becomes costal. The costal type is seen to occur where 

 air can not pass freely into the thorax or where the diaphragm 

 or adjacent organs are diseased, (abdominal tumors, ascites, 

 tympanitis). 



When the abdominal muscles are more active in produc- 

 ing the respiratory movement than the thoracic muscles the 

 type of breathing becomes abdominal. The abdominal 

 type prevails when painful conditions of the chest wall are 

 present and where expiration is difficult, as in pulmonary 

 emphysema (heaves). 



T'here is sometimes observed in animals a condition which 

 corresponds to hiccoughs (singultus) in man. It is charac- 

 terized by a rhythmic, spasmotic contraction of the diaphragm 



