=Subacute Laryngitis.= This form has been chiefly seen in young animals and up to eight years old. At the outset its symptoms are moderate but as it is usually associated with serous effusions in and around the mucous membrane the symptoms above mentioned as indicating imminent danger of suffocation may suddenly appear and life can only be preserved by opening the trachea. =Chronic Laryngitis.= This may follow the acute form or it may come on independently and by slow degrees. It may accompany nasal catarrh, or chronic bronchitis. Old animals which have had heavy draught work and repeated attacks of sore throat, are frequent subjects of it, and as Fergusson has pointed out it is most prevalent among horses whose throats have been compressed by the inconsiderate use of the bearing rein. Reynal has observed it often in horses that are sweated with difficulty, and in those which remain long wet from the length and thickness of their winter coats. _Symptoms._ When acute laryngitis passes into the chronic form all the symptoms subside except a slight nasal discharge, the cough, tenderness of the larnyx, and _roaring_. The cough is dry, short, and hacking, rarely soft, and is heard mainly when the animal feeds, when he leaves the hot stable for the cold air, and after drinking cold water. During exercise, it is equally excited, the cough becoming harder, and the horse extending his head and neck as if to disengage some body from its throat. The subject may in nearly all other respects maintain the appearance of vigorous health. _Course, etc._ This disease is liable to prove obstinate and if of old standing, often incurable. Unless checked, the continued congestion and irritation of the larynx, the frequent, hacking cough, and the consequent violent distension of the lungs bring about extensive and irreparable structural changes. Among these may be mentioned ossification of the cartilages of the larnyx; paralysis of the left laryngeal nerve with wasting of the muscles to which it is distributed, and _roaring_; dilatation of the bronchial tubes, and permanent distension and rupture of the air cells (emphysema, broken wind, heaves).