DISEASES OF THE HOESE. 131 



Give a powder ever}^ night and morning mixed with bran and oats, if 

 the animal will eat it, or shaken with about a pint of flaxseed tea and 

 administered as a drench. 



If the cough remains after the horse is apparently well, give 1 dram 

 of iodide of potassium dissolved in a bucketful of drinking water one 

 hour before each meal for two or three weeks if necessary. Do not 

 put the animal to work too soon after recovery. Allow ample time to 

 regain strength. This disease is prone to become chronic and may 

 run into an incurable case of thick wind. 



PLEURISY. 



The thoracic cavity is divided into two lateral compartments, each 

 containing one lung and a part of the heart. Each lung has its sepa- 

 rate pleural membrane, or covering. The pleura is the thin glistening 

 membrane that covers the lung and also completely covers the internal 

 walls of the chest. It is very thin, and to the ordinary observer appears 

 to be part of the lung, which, in fact, it is for all practical purposes. 

 The smooth, shiny surface of the lung, as well as the smooth, shiny 

 surface so familiar on the rib, is the pleura. In health this surface is 

 always moist. A fluid is thrown off by the pleura, which causes the 

 surface to be constantly moist. This is to prevent the effects of fric- 

 tion between the lungs and the walls of the chest and other contiguous 

 parts which come in contact. It must be remembered that the lungs 

 are dilating each time a breath is taken in, and contracting each 

 time a breath of air is expelled. It may be readily seen that if it were 

 not for the moistened state of the surface of the pleura the continual 

 dilation and contraction and the consequent rubbing of the parts against 

 each other would cause serious friction. 



Inflammation of this membrane is called pleuris}-. Being so closely 

 united with the lung, it can not alwaj^s escape participation in the 

 disease when the latter is inflamed. Pleurisy may be due to the same 

 predisposing and exciting causes as mentioned in the beginning of this 

 work as general causes for diseases of the organs of respiration, such 

 as exposure to sudden changes of temperature, confinement in damp 

 stables, etc. It may be caused by wounds that penetrate the chest, for 

 it must be remembered that such wounds must necessarily pierce the 

 pleura. A fractured rib may involve the pleura. The inflammation 

 following such wounds may be circumscribed, that is, confined to a 

 small area surrounding the wound, or it may spread from the wound 

 and involve a large portion of the pleura. The pleura may be involved 

 secondaril}" when the heart or its membrane is the primary seat of the 

 disease. It may occur in conjunction with bronchitis, influenza, and 

 other diseases. Diseased growths that interfere with the pleura may 

 induce pleurisy. The most frequent cause of pleurisy is an extension 

 of inflammation from adjacent diseased lung. It is a common com- 



