24 THE PRACTICE OF VETERINARY MEDICINE; 



exerts a powerful influence in this direction. Animals 

 having a long neck and narrow in the submaxillary space 

 should always be regarded with suspicion ; for although 

 such au animal is not by any means necessarily a roarer, he 

 is undoubtedly predisposed to the disease. Tight reining 

 may also be regarded as a fruitful cause of roaring. Another 

 theory propounded recently is that the recurrent branch of 

 the pneumogastric nerve, being influenced by the lymphatic 

 glands, which lie in close proximity to its course, becomes 

 irritated ; irregular nervous action is the result, and the 

 laryngeal muscles, on account of perverted nutrition, undergo 

 fatty degeneration, or become wholly or partially paralyzed, 

 in consequence of which the disorder known as roaring 

 becomes established. When caused by strangles, it is 

 generally due to the form known as irregular. 



Symptoms. — It is only when the animal is excited or 

 sharply exercised that the sound is produced. In ordinary 

 cases it is only during inspiration that the sound is made, 

 but in bad cases the sound is emitted also during the per- 

 formance of the expiratory act. A moderate canter is not 

 always sufficient to expose the roarer. The proper way to 

 examine for and discover roaring is as follows : — 



The animal should be made to attain as high a degree of 

 excitement as possible, then should be galloped past the 

 examiner at full speed, and preferably on an ascending 

 grade. The animal, after one or two runs, may be pulled 

 up shortly, close to the examiner, who, by immediately 

 placing his ear to the nostrils and larynx of the animal, 

 will be able to detect any abnormal sound. The above 

 method of examination is to be recommended in all cases, 

 as some cases of roaring are so slight as to be barely dis- 

 coverable by the most severe tests. Another way to test an 

 animal for roaring is as follows : Have the animal gently 

 trotted, after which he is to be coughed, due observation 



