DISEASES OF TUE RESPIRATOKV OKUANS. 131 



CHRONIC COUGH. 



A chronic cough may succeod the acute disease of tlie lespiratorv 

 organs, such as i)ncuni()uia, bronchitis, hiryngitis, etc. It accom- 

 panies chronic roaring, chronic broncliitis, 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 

 syuiptom of chronic indigestion or of worms. In such cases it is 

 causetl by a retlex ner\t)us 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 atfections will be found under their appro- 

 l)riate 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 siuiilar 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 

 j)ossil)le. 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 ellusion into 

 the chest, and by the existence of rheumatism in other parts. The 

 tieatment for this affection is the same as for rheunuitisni affecting 

 other parts. 



WOUNDS PENETRATING THE WALLS OF THE CHEST. 



A wound i)enetrating 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 collai)se of the lung. The wound may be 

 .St) made tluit 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 (|uantity of air gains access with each inspira- 

 tion, while none is allowed to escape until the lung is pre.s.sed into a 

 very .small compass and ff)rced into the anterior jiart of the chest. 

 The same thing may occur from a l)roken rib inflicting a wound in 

 the lung. In this form the air gains access from the lung, and there 

 mav not be even an opening in the walls of the chest. In such ca.ses 

 the air may be absorbed, when a spontaneous cure is the result, but 



