CHAPTER VL 



ANATOMY AND PHYSIOLOGY OF THE LARYNX. 



Before attempting to deal with the special morbid condi- 

 tions which cause chronic Roaring, it is requisite to under- 

 stand the construction and functions of the larynx — the 

 part which is chiefly involved, and that in which the noise 

 is produced. This study is all the more necessary in order 

 to arrive at a correct knowledge of the medical and surgical 

 treatment which must be adopted in order to remove the 

 impediment to respiration, and thus restore the unsound 

 horse to such a state of soundness as will enable it to 

 perform useful service. 



It must be remembered, also, that without a correct 

 knowledge of the anatomy and physiology of the organs of 

 respiration, it is impossible to get beyond the mystery which 

 has so long encompassed the origin of Roaring in the horse 

 — a mystery which largely prevails in many quarters, and 

 which obscures the pathology of the disease to a most 

 damaging extent. If certain evidence is to be accepted, we 

 would appear to be no more advanced in this direction than 

 was Percivall fifty years ago, who, when noticing the ap- 

 pearances presented by the larynx of a horse which had 

 been affected in this way, writes : " How we are to account 

 for these changes, to what original cause refer them, is as 

 yet unknown : by some they are loosely spoken of as the 

 ultimate consequences of paralysis or of spasm ; but though 

 these tales may satisfy their employers, they are no more 

 to the profession than the baseless conjectures of their 

 authors, and as such are deserving of no comment. "^ 

 1 " Elementary Lectures on the Veterinary Art," part ii., p. 254, 1824. 



