DISEASES OF THE KESPIKATORY SYSTEM. 145 



On palpation they have a good deal of resistance, and pit some- 

 what on pressure; they are very light, and it' a piece be cut oil" it 

 will float on water; it crepitates when cut. In the anterior, middle, 

 and posterior borders, the air-cells are enlarged. 



If it is the interlobular variety of emphysema, elevations which 

 contain air can be seen over the surface of the lungs; these eleva- 

 tions are often white, and old practitioners thought they were tuber- 

 cles; if cut, they contain air, press on them, and the air will run 

 under the pleura. 



What are the symptoms ? 



These are very interesting for us, especially in cases of exam- 

 ination for soundness, as such horses are to he considered unsound. 



The disease comes on slowly or suddenly. The derangement 

 occurs in the mechanism of the respiratory movements which can 

 often be detected by simple inspection of the abdominal walls in the 

 region of the flank. The alteration is principally in the expiratory 

 movements. Normally, there is an inspiration, an expiration, and 

 then a pause; in this disease, during the expiration (falling in of the 

 hypochondriac region, hollowing of the upper part of the flank), 

 there is a short pause and a secondary expiratory movement. There 

 is a well-marked line or groove produced by the muscles along the 

 abdomen. 



The double, or the two movements in the expiratory act, is not 

 pathognomonic of heaves, as it may be seen in cases of pleurisy as 

 well as in a rupture of the diaphragm and hernia of the intestines 

 preceding death. 



Inspiration is difi'erent; the ribs are elevated more; they seem 

 to turn on their axis; the posterior border of the ribs turns upward 

 and outward; at the end of expiration there is a jump of the 

 abdominal cavity in some cases; it is a peculiar jerky movement, 

 a falling back of the intestines; this movement may be so severe 

 as to cause a movement of the animal; if the animal be hitched to 

 a cart, the cart moves. 



In severe cases there is a dilatation of the nostrils, which keep 

 open and do not recede; on a frosty day the column of air is divided, 

 or in the summer-time by placing the hand to the nostril you can 

 feel the interrupted volume. 



In other cases there is a well-marked play of the anus; the 

 anus goes back and forward; this is not pathognomonic, as it is also 

 seen in pleurisy. 



