118 DISEASES OF THE HOESE. 



the anatomical arrangement of the nerves. The left nerve is much 

 longer and more exposed to interference than the right nerve. 



In chronic roaring there is no evidence of any disease of the larynx 

 other than the wasted condition of the muscles in question. The 

 disease of the nerve is generally located far from the larynx. Dis- 

 ease of parts contiguous to the nerve along any part of its course 

 may interfere with its proper function. Enlargement of lymphatic 

 glands within the chest through which the nerve passes on its way 

 back to the larynx is the most frequent interruption of nervous sup- 

 ply, and consequently roaring. When roaring becomes confirmed, 

 medical treatment is entirely useless, as it is impossible to restore the 

 wasted muscle and at the same time remove the cause of the interrup- 

 tion of the nervous supply. Before roaring becomes permanent the 

 condition may be benefited by a course of iodide of potassium, if 

 caused by disease of the lymphatic glands. Electricity has been used 

 with indifferent success. Blistering or firing over the larynx is, of 

 course, not worthy of trial if the disease is due to interference of the 

 nerve supply. The administration of strychnia (nux vomica) on the 

 ground that it is a nerve tonic with the view of stimulating the af- 

 fected muscles is treating only the result of the disease without con- 

 sidering the cause, and is therefore useless. The operation of extir- 

 pating the collapsed cartilage and vocal cord is believed to be the 

 only relief, and, as this operation is critical and can only be per- 

 formed by the skillful veterinarian, it will not be described here. 



From the foregoing description of the disease it will be seen that 

 the name " roaring," by which the disease is generally known, is only 

 a symptom and not the disease. Chronic roaring is also in many 

 cases accompanied by a cough. The best way to test whether a horse 

 is a " roarer " is either to make him pull a load rapidly up a hill or 

 over a sandy road or soft ground ; or, if he is a saddle horse, gallop 

 him up a hill or over soft ground. The object is to make him exert 

 himself. Some horses require a great deal more exertion than others 

 before the characteristic sound is emitted. The greater the distance 

 he is forced, the more he will appear exhausted if he is a roarer; in 

 bad cases the animal becomes utterly exhausted, the breathing is 

 rapid and diiScult, the nostrils dilate to the fullest extent, and the 

 animal appears as if suffocation was imminent. 



An animal that is a roarer should not be used for breeding pur- 

 poses. The taint is transmissible in many instances. 



Grunting. — A common test used by veterinarians when examining 

 " the wind " of a horse is to see if he is a " grunter." This is a sound 

 emitted during expiration when the animal is suddenly moved, or 

 startled, or struck at. If he grunts he is further tested for roaring. 

 Grunters are not always roarers, but, as it is a common thing for a 

 roarer to grunt, such an animal must be looked upon with suspicion 

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