152 DISEASES OF THE RESPIRATORY ORGANS 



present any change except the signs of jDartial compression. The other 

 organs of the body are aneemic. 



Clinical Symptoms. — The physical examination of this disease pre- 

 sents symptoms ver}- similar to pleuritic exudates, but the change takes 

 place quickly, and fever and cough are absent, but in dropsical transudates 

 both sides of the thoracic cavity are filled, and on changing the position 

 of the animal the fluid moves about much more quickly than a pleuritic 

 exudate would, and the sensitiveness of the animal to pressvire on the 

 Avails of the chest and the rubbing or crepitating bruit of pleuritis is 

 absent. 



Therapeutics. — The treatment, as a rule, is of a palliative character, 

 as it is only in very rare instances that we succeed in removing the 

 original disease; but we may use the same agents as in ascites. The op- 

 eration of tapping the chest wall (see puncture of the cavity of the chest, 

 page 150) is only to be resorted to when the fluid has collected in large 

 quantities and the animal is threatened with suffocation; but this only 

 affords temporary relief. 



Other Diseases of the Pleura. 



Pneumothorax. — Etiology. — The cause of pneumothorax, that is to 

 say, the accumulation of air in the thorax, is produced in several ways; 

 by perforating wounds of the chest, by the breaking into the pleural 

 cavity of a collection of pus from the lung, by tearing of the lung tissue 

 from great exertion, and from perforation of the oesophagus or pharynx. 

 Careless puncture of the chest wall, fracture of ribs, perforation of the 

 bronchi by a foreign body, which finds its way into that part, or it may 

 also be caused by degeneration of the pleuritic effusion, causing the for- 

 mation of gas. 



Pathological Anatomy. — On making an opening into the chest with 

 trocar and canula, the air escapes with a hissing sound; if the collection of 

 air is great, the lungs are pushed out of position, interfering greatly with 

 respiration. If this condition exists for any length of time, a purulent, 

 and, in rare cases, a sero-purulent, pleuritis is developed, caused by the 

 presence of some irritant agents that have gained admittance into the 

 cavity besides air. 



Clinical Symptoms and Course. — There is great difficulty in respira- 

 tion, and the affected side of the chest wall is visibly distended, and during 

 respiration it remains almost stationary. When the heart is pushed out 

 of position there is a peculiar tympanitic sound, the pulsations have a 

 metallic echo, and the respiratory bruit is absent. In some rare cases 

 we hear a metallic bruit; this is caused by the entrance of air directly 

 into the pleural cavity with each inspiration. 



