TUBERCULOSIS OF THE RESPIRATORY APPARATUS. 691 



rough. The least irritation brings on these attacks of coughing ; 

 changes from the warmth of the stable to the coldness of the outer 

 air or rice versa, the presence of dust or the action of liquids when 

 drinking, etc., etc. During the first stage coughing is not followed 

 by expectoration, but later yellowish-grey, glairy mucus may be dis- 

 charged : more frequently it is coughed into the pharynx and swallowed. 



These symptoms continue for weeks or months without showing 

 any tendency to abate. If the larynx is attacked inspiration becomes 

 rattling and difficult, while the neck and head are held extended, and 

 the least pressure over the larynx produces coughing. 



Tuberculosis of the larynx, trachea, and bronchi is usually accom- 

 panied by disease of the lung, but may occur by itself. 



When there is a discharge it consists of thick, viscous, sticky 

 mucus of a peculiar greyish-yellow colour. Microscopical examination 

 shows it to contain tuberculous bacilli. 



Pulmonary Tuberculosis usually assumes the chronic form, and is 

 almost always preceded by specific bronchitis. The patients retain 

 their appearance and condition for a longer or shorter time, and, 

 without the experience resulting from continued observation, it would 

 be difficult to believe them to be suffering from the slow development 

 of a serious disease. 



Frequent coughing without any apparent reason is the only symptom 

 likely to arouse suspicion. 



At a later stage these animals lose condition, feed less eagerly or 

 exhibit capricious appetite, and sometimes well-marked and repeated 

 digestive disturbance, such as slight tympanites with constipation or 

 diarrhoea, moderate impaction of the rumen, relative atony and 

 slackening of peristaltic movements. The wasting gradually becomes 

 more marked or, in the case of pregnant or milch cows, makes 

 intermittent progress, until the animals become ansemic and finally 

 cachectic. The cough is more frequent and more severe, and is 

 followed by discharge from the nose or by swallowing movements. 

 From this time phthisis, properly so called, exists. 



The course of the disease is not invariable. Certain animals may 

 appear ill for years without clinically showing the least apparent 

 aggravation ; others on the contrary, though living under similar 

 conditions, are rapidly attacked, and in six to twelve months exhibit 

 all the signs of advanced phthisis. Pregnancy, suckling, and pro- 

 longed lactation favour the development of the disease by taxing 

 the physical resources of the animal. 



Animals suffering from phthisis exhibit a pecuhar appearance. 

 They are extremely thin, all their soft tissues are wasted, the Hmbs 

 are dragged in moving, respiration is rapid and sometimes jerky, 



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