Symptoms. 



167 



When the amount of exudate is very great, changes in the 

 shape of the thorax may appear. In smaller animals an en- 

 largement of the affected half of the chest is occasionally seen 

 distinctly, while the intercostal spaces of larger animals may 

 be flattened or even protruding. In some cases, especially in 

 larger animals, non-painful edemata are seen on the anterior 

 thorax, the lower thorax or even on the alxlomen. 



The tenderness on pressure of the intercostal spaces de- 

 creases or disappears entirely in the region of the fluid exu- 

 date. It persists, however, in the higher portions of the thorax 

 if these are the seats of dry pleuritis. The painful character 

 of the cough persists also in the further course. 



Percussion shoAvs a horizontal dullness either on one or 

 both sides of tlie chest (Fig. 25), with a considerable increase 



Fig. 26. Horizontal line of dullness in pleurisy in sitting posture of the ani- 

 mal. (The same as in Fig. 25.) 



in resistance. Parallel with the boundary of complete dullness 

 and extending some centimeters upward there is some dullness, 

 followed by a normal sound. If, however, the dullness extends 

 over the lower half of the thorax, the percussion sound of the 

 other half is diminished, because the high column of the fluid 

 also interferes with the vibrations of the free portion of the 

 wall of the thorax. When larger animals lie down, the area 

 of dullness becomes diminished or it may occasionally disap- 

 pear entirely and it changes also in smaller animals with 

 changes of position of the body (Fig. 26). In case of an en- 



