Symptoms. 733 



sound. Now and then, cases are met with in which the partic- 

 ular sound is audible even while the animals are at rest, or from 

 the slightest stimulation of any kind. Cases are very rare in 

 which owing to bilateral paralysis there is a sound during 

 expiration due to stenosis of the glottis. It is easy to prove 

 that the sound is influenced by the quantity of air entering the 

 trachea and the rapidity mth which it is taken in. If one 

 nostril of a roarer be closed or both of the nostrils are par- 

 tially closed the noise due to the stenosis disappears immedi- 

 ately. In this lies the explanation of the fact that the sound 

 ceases immediately after the animal stops, or at the latest with- 

 in 5 to 8 minutes after. 



Respiration is more or less difficult during severe exertion. 

 Simultaneously with the appearance of the sound, symptoms 

 of dyspnea set in, the nostrils are opened out in a trumpet-like 

 manner, the ribs are raised spasmodically, the flexible por- 

 tions of the chest wall sink inwards at each inspiration, and 

 the anus moves in and out with each inspiration and expira- 

 tion respectively. If the work be continued there may, in severe 

 cases, be s;^anptoms suggestive of suffocation and the horse 

 may fall down. The difficulty of respiration soon disappears, 

 and within one to five minutes after the animal stops, there 

 may be only as much deviation from quiet respiration as is 

 seen in sound horses under the same conditions. 



During rest symptoms are either very slight or quite ab- 

 sent. In somewhat more advanced cases it is often difficult to 

 make animals cough, but the cough in such cases is deep, pro- 

 longed and rattling. This is proof that the glottis cannot be 

 closed and the paralyzed and relaxed vocal cord makes slow 

 oscillations. So long as the vocal cord is sufficiently tense to 

 allow of closure of the glottis the cough does not show the 

 characters described. In many cases the neigh is more hoarse. 



Since the irritability of the sensory nerves tends to be exaggerated before 

 conductivity is lost there is a dry cough which is not associated with any discharge 

 from the nose before the onset of paralysis and for some time after. This cough 

 can be caused far more easily than normally. Some authors have observed catarrh 

 of the larynx before the onset of symptoms of paralysis. 



In many cases the arytenoid cartilage of the left side can 

 be pressed more easily into the cavity of the larynx, by palpat- 

 ing the larynx, causing a whistling or rattling inspiration. 

 Palpation of both sides frequently reveals atrophy of the 

 muscle on the left side. 



Examination of the larynx with the laryngoscope shows 

 that one vocal cord, generally the left, moves only slightly 

 during respiration, or remains motionless in the middle line, 

 or in cases in which the dilator alone is paralyzed it remains ver- 

 tical. In cases of bilateral paralysis both the vocal cords move 

 sluggishly or remain motionless. In view of the fact that with 

 the laryngoscope a bird's-eye view of the larynx is obtained, 

 slight dropping of the arytenoid cartilage cannot be deter- 



