ACUTE DISEASES OF THE ORGANS OF RESPIRATION. 205 



tions proceed from inflammation of the mucous membrane of the parts, 

 and as both parts are usually affected at the same time, they generally 

 exist in combination, and we may therefore for practical purposes treat 

 these affections as one disease. 



417. Causes. 



Laryngitis and Sore throat generally have their origin in atmospheric 

 causes. Humidity of the atmosphere is the most common cause ; but 

 any sudden change, especially from dry to wet, is apt to bring on these 

 affections. Inasmuch, however, as we seldom find horses at grass affected, 

 it is evident that such changes, though predisposing causes, are rarely 

 sufficient of themselves to induce these diseases. In further confirmation 

 of this view we may remark, that horses turned out to grass from stables 

 even in cold weather rarely suffer from them. 



Artificial causes, such as bad ventilation and bad stable management, 

 are needed to aggravate the natural predisposition. The reader will 

 readily understand, that whilst a certain amount of bad air, containing 

 ammonia and other emanations commonly found in badly-kept stables, 

 may not seriously affect the membrane as long as its secretions are suffi- 

 cient and healthy, yet the same amount of noxious causes may be power- 

 ful enough to set up irritation in the part when the membrane and its 

 secretions are even in a slight degree deranged. 



Again, neglect on the part of a servant in allowing a horse on his 

 return from work to stand in the stable without being dried at once, or 

 carelessness on the part of the rider in allowing a sweating horse to 

 stand in a draught or in the sun, and all such acts of mismanagement, 

 are apt to bring on these affections, especially at those seasons of the 

 year when, as in spring and autumn, the skin is very sensitive. Horses 

 which are long in the windpipe or which have lost a vein, are predis- 

 posed to these diseases. 



Horses brought from grass and put into a warm stable are peculiarly 

 liable to be affected in the membrane of the throat, on account of the 

 change from the pure cool air to the heated and often vitiated atmo- 

 sphere of the stable. 



In some very few cases Laryngitis or Sore throat may be caused by 

 the irritation arising from the accidental presence of some foreign body 

 in or about the larynx or pharynx, or from external injuries. 



418. Symptoms. 



The earliest symptoms of Laryngitis combined with Sore throat are 

 cough and difficulty of swallowing solids or even liquids. The mouth is 

 hot and the horse is disinclined to eat, or perhaps " quids " his hay, i. e. 

 lets the masticated hay fall out of his mouth. He only sips his water, 

 or takes it by small mouthfuls. The region of the gullet and fauces is 

 hot and tender, and the least pressure on it often produces a paroxysm 

 of coughing. The salivary glands throughout are swollen and tender. 

 The difficulty in swallowing arises from the irritated state of the mem- 



