CHAPTER II. 

 DISEASES OF THE LARYNX. 



LARYNGITIS. 



Clinically laryngitis may be classified into : 

 Catarrhal (acute and chronic). 

 Croupous. 

 Edematous. 



Catarrhal Laryngitis. — Definition. — ^A superficial inflamma- 

 tion of the mucosa of the larynx. Usually the upper part 

 of the trachea and often the pharynx are also involved 

 (laryngotracheitis, laryngopharyngitis) . 



Occurrence. — Catarrhal laryngitis is one of the commonest 

 diseases of horses and cattle. It frequently assumes an 

 enzootic form, being very prevalent during the changeable 

 weather of spring and fall. The disease may be primary or 

 secondary. 



Etiology. — ^The causes of primary laryngitis are : Refrigera- 

 tion, inhalation of irritant dust, gases, ingestion of ferment- 

 ing foods (brewer's grains, distillery slops, potato residue), 

 continued bellowing of cattle, throat latch of bridle too 

 tight, and primary infections. 



Secondary laryngitis accompanies many of the infectious 

 diseases, especially influenza and strangles of the horse, 

 tuberculosis of the ox, cholera of swine, and verminous 

 bronchitis of sheep. A spread of inflammation from neigh- 

 boring organs (pharynx, trachea) may induce laryngitis. 

 The causes of chronic catarrhal laryngitis are the same 

 as those of the acute form, the irritant acting mildly but 

 repeatedly or persistently. 



Symptoms. — ^A dominant sjToptom of laryngitis is a dry, 

 harsh cough which the patient seeks to suppress. It is 

 especially noticeable when the animal is brought out into 



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