138 DISEASES OF THE RESPIRATORY ORGANS 



secretion is clammy, slimy, or shining, in some cases it is bad-smelling or 

 even putrid, similar to atelekase. 



In old cases of chronic bronchitis, there may be some stenosis of the 

 tubes, and also, from the constant irritation of the bronchia, emphysema 

 of the lungs. In regard to this the reader is referred to works on patho- 

 logical anatomy. 



Stenosis (contraction) of the bronchia may be caused either by swell- 

 ing of the bronchial mucous membrane or by the collection of masses of 

 thickened secretion in the tulje. In some cases, the two causes acting 

 together exclude the air from the alveoli of that part of the lungs to 

 which the affected l^ronchia carry the air, causing the lung-tissue 

 to collapse. This condition, which originates in the manner de- 

 scribed, does not change its structure, but soon becomes solidly filled 

 with blood. 



In all chronic conditions, we also find the opposite of stenosis, that 

 is, bronchiectasis (widening of the bronchial tubes) ; this is caused by a 

 relaxed condition of the bronchial walls, due to the chronic irritation and 

 also to the pressure of collections of the secretions. This dilatation of 

 the tubes may be either cylindrical or spindle-shaped. 



Emphysema of the Lungs. — This is found near the atelectatic centres 

 and on the borders of the lungs; this condition is supposed to be caused by 

 violent coughing spells and also b}" bronchitis. The affected parts do not 

 collapse, but appear soft, clear and bloodless; they will, however, coh 

 lapse cpiickly on incision. 



Clinical Symptoms and Course. — These vary, according to the 

 amount and location of the irritation, whether it is in the trachea, large, 

 medium, or small lironchia, and whether it is acute or chronic. 



'1. Acute Catarrh of the Large Bronchia. — This commences with slight 

 and frequent chills, accompanied by fatigue, indfference, depression, loss 

 of appetite, and sometimes with a stiff and strained gait and slight rise of 

 temperature, which may rise to 40° C. Soon afterward the animal com- 

 mences to cough; this is one of the principal symptoms of the disease. In 

 the beginning it is short, painful and dry, later it becomes moist and more 

 frequent. It can easily be started by slight pressure on the trachea and 

 also by tapping on the chest close behind the shoulder. 



Percussion, as a rule, does not reveal the full extent of the disease. 

 On auscultation, in mild cases, we hear an increased A'esicular respiration 

 in the trachea and large bronchia, and when the medium-sized bronchia are 

 affected there is an accumulation of mucus in the tubes and the A'csicular 

 murmur is increased. This is due to the fact that while the l:)ronchitis is 

 in the dry stage the sounds are roaring or snorting in character, and when 

 the fluid mucus has accunudated the sounds liecome rattling, as if the 

 air was passing through a thick mucus (mucous rales.) 



