30 



DISEASES OF THE DIGESTIVE APPARATUS. 



produced in animals by the experiment of Dr. Sanderson, which 

 consists in the local application of oil of cantharides, but the false 

 membranes thus produced have a greater tendency to organize. 

 — w. L. z.] 



Etiolog'y. Pharyngitis appears at times as a sporadic disease, 

 at other times it is contagious. It is frequently found in the pig 

 and horse, less often in the ox and dog ; it is very rare in sheep. 

 A certain individual predisposition, which has been proved to 

 exist also in man, is one of the general causes, and is apt to favor 

 its development ; but the exact nature of this predisposition is not 

 better known in animals than in man. At all events, weak, deli- 

 cate, and young animals are more frequently affected by pharyn- 

 gitis, than are old, adult, or strong horses ; these, however, are not 

 exempt from it. 



The principal causes determining it are : 



1. Mechanical, chemical, and thermic irritations, acting directly 

 upon the mucous membrane. In the first division we must mention 

 wounds and contusions produced by irritating bodies ; sharp 

 bones, fish-bones, thorns, needles, coarse food, barley balls ; un- 

 skilled filling of the teeth, and also gad-fly larvae in the mucous 

 membrane (Garnier, Pigeaire, Mather, Christeusen). Prominent 

 tumors in the pharynx, especially actinomycomas and tuberculous 

 neoformations in the ox, can also produce catarrh of the pharyn- 

 geal mucous membrane. As chemical irritants, we must point 

 out non-dissolved emetic drinks, concentrated croton oil, ammonia 

 not sufficiently diluted; phosphoric preparations, and food and 

 drinks that are too hot. 



2. Local cold, caused by breathing very cold air, especially 

 during north or northeast winds (Schmidt) ; icy drinks and fod- 

 der covered with frost, under certain conditions, can produce 

 pharyngitis. A common cold, rain, and sudden changes of tem- 

 perature are enough to determine it. Too much importance has 

 undoubtedly been ascribed to the influence of cold by the old 

 school (diseases a frigore), but this etiological factor must not be 

 altogether dropped in the present state of science ; especially must 

 it be taken into consideration in the pathology of pharyngitis. 



3. The propagation of pharyngitis from contiguous inflammation. 

 We have already described the influence of stomatitis, rhinitis, and 

 laryngitis in the genesis of pharyngeal angina. It may appear 

 during the course of any common disease. We know the pharynx 



