DISEASES OF THE RESPIRATORY ORGANS, 131 
CHRONIC COUGH. 
A chronic cough may succeed the acute disease of the respiratory 
organs, such as pneumonia, bronchitis, laryngitis, etc: It accom- 
panies chronic roaring, chronic bronchitis, broken wind; it may 
succeed influenza. As previously stated, cough is but a symptom and 
not a disease in itself. Chronic cough is occasionally associated with 
diseases other than those of the organs of respiration. It may be a 
symptom of chronic indigestion or of worms. In such cases it is 
caused by a reflex nervous irritation. The proper treatment in all 
cases of chronic cough is to ascertain the nature of the disease of 
which it is a symptom, and then cure the disease if possible and the 
cough will cease. 
The treatment of the affections will be found under their appro- 
priate heads, to which the reader is referred. 
PLEURODYNIA. 
This is a form of rheumatism that affects the intercostal muscles; 
that is, the muscles between the ribs. The apparent symptoms are 
very similar to those of pleurisy. The animal is stiff and not in- 
clined to turn round; the ribs are kept in a fixed state as much as 
possible. If the head is pulled round suddenly, or the affected side 
struck with the hand, or if the spaces between the ribs are pressed 
with the fingers, the animal will flinch and perhaps emit a grunt or 
groan expressive of much pain. It is distinguished from pleurisy 
by the absence of fever, cough, the friction sound, the effusion into 
the chest, and by the existence of rheumatism in other parts. The 
treatment for this affection is the same as for rheumatism affecting 
other parts. 
WOUNDS PENETRATING THE WALLS OF THE CHEST. 
A wound penetrating the wall of the chest admits air into the tho- 
racic cavity outside the lung. This condition is known as pneumo- 
thorax and may result in collapse of the lung. The wound may be 
so made that when the walls of the chest are dilating a little air is | 
sucked in, but during the contraction of the wall the contained air 
presses against the torn part in such manner as entirely to close the 
wound; thus a small quantity of air gains access with each inspira- 
tion, while none is allowed to escape until the lung is pressed into a 
very small compass and forced into the anterior part of the chest. 
The same thing may occur from a broken rib inflicting a wound in 
the lung. In this form the air gains access from the lung, and there 
may not be even an opening in the walls of the chest. In such cases 
the air may be absorbed, when a spontaneous cure is the result, but 
