734 Paralysis of the Kecurreiit Xerve. 



mined, but it may )je suspected in many cases, owing to asym- 

 Pietry of tlie larynx, the ary-epigiottic fold appearing shorter 

 and curved in its hinder part. 



Immobility of the vocal cords caused by paralysis must not be confused with 

 the position occupied by them during prolonged inspiration, for in the former case 

 they are unable to make any movement, while in the latter pressure on the nasal 

 septum, blowing into the nose, drawing one or two straps tight round the thorax 

 are sufficient to set the vocal cords in motion again (Malknuis). 



According to Bassi the condition of the vocal cords in horses can be ex- 

 amined by introducing a brilliant light into the posterior portion of the widely 

 opened mouth. This plan, although useful in small animals is impracticable in the 

 horse, the different portions of the larynx not being visible owing to the length of 

 the soft palate. 



Course. In the great majority oi ^ases the disease is 

 chronic. It is only very occasionally that the condition appears 

 suddenly with pronounced symptoms of illness, persists for 

 several weeks and then gradually disappears or becomes chron- 

 ic. Such cases have been recorded by a number of authors 

 (Giinther, Lies, Vollers, Alberts, Albrecht, Malkmus, Friis, 

 Miiller and others). Malkmus, from the findings in one case 

 carefully examined with the laryngoscope, describes a complete 

 bilateral paralysis as opposed to the usual nnilateral chronic pa- 

 ralysis, in which there is a possibility of recovery. With the 

 exception of these very rare cases the progress of the disease 

 is slow. S^^nptoms appear at the most four to six weeks after 

 the commencement of the disease process and reach their 

 maximum after a long time, sometimes one to two years. 

 Sometimes paralysis makes its appearance ten to eleven days 

 after the appearance of the primary disease (Rosenfeld, Froli- 

 ner). The sound due to stenosis increases from this time on- 

 wards, in constantly shorter intervals during work, until a few 

 paces are sufficient to cause a loud roaring and s^miptoms of 

 dyspnea. 



Diagnosis. Paralysis of the vocal cords or their muscles 

 can l)e determined with certainty only by examination with the 

 laryngoscope, and in small animals by direct inspection. If it 

 is possible to press the arytenoid cartilage easily into the 

 larynx or if atrophy of the muscle on the outer surface of the 

 cartilage can be detected one may form the opinion that the 

 disease is in existence, but this can only be done in advanced 

 cases, and the possibility of error is not excluded. Coughing 

 is of only slight value from the point of view of diagnosis be- 

 cause it is difficult or impossible to make many sound horses 

 cough. If parah^sis exists already, the cough may not be spe- 

 cially characteristic, and on the other hand, there may be the 

 peculiar type of cough in other diseases of the larynx. 



With a probability that amounts almost to certainty the 

 disease may be diagnosed when some other disease is or has 

 lieen in existence which experience has shown may be followed 

 by paralysis of the recurrent nerve (strangles, pneumonia, 

 neoplasms, aneurism, etc.). In the absence of such information 



