DISEASES OF THE KESPIKATORY OEGANS. 585 



roarers become bad tlirivers, and often succumb to trivial 

 diseases. 



Eoaring being due to a progressive disease, it is necessary that 

 the veterinarian should reject as unsound every animal which 

 makes the slightest roarin2; or whistlincf sound in its breathing. 



COUGH AS INDICATIVE OF DISEASE. 



Cough is the sound produced in the larynx by the violent 

 expulsion of air from the lungs, and is symptomatic of various 

 diseases. Cough is divided into dry and moist. 



Dry cough is divided into short, hacking, liollow, broken- 

 winded, and spasmodic. The dry cough is symptomatic of 

 irritation and dryness of the respiratory mucous membrane. 

 In the early stages of laryngitis it is loud and long, becoming 

 afterwards rasping and then moist. In chronic disease of tlie 

 larynx it is loud, roaring, and often hollow. In the early 

 stages of bronchitis it has a hollow metallic sound; it after- 

 wards becomes moist, and is more or less painful throughout 

 the disease. In pneumonia the cough is short, seems as if 

 proceeding from a solid organ, and is accompanied in the later 

 stages by a rusty, tenacious expectoration. 



Tlie cough of pleurisy is dry throughout, is painful, hacking, 

 sometimes as if cut in two, the animal being seemingly afraid to 

 complete the act by one effort. 



The Irohen-winded cough is at first spasmodic, becoming, as 

 the disease advances, feeble, short, and single, the animal being 

 unable to reheve itself by the action of the chest and lungs ; 

 hence the suppressed cough becomes diagnostic. 



The hollovj cough, a sepulchral sound, varying in intensity, 

 indicative of chronic disease, and on this account is termed a 

 " chronic cough." 



The moist coughs indicate an inflamed and humid condition of 

 the respiratory mucous membrane. 



There are various other kinds of coughs associated with dis- 

 eases of the heart, digestive organs, and the process of dentition; 

 these are valuable as aids to diagnosis, when studied in connec- 

 tion with other symptoms. They are mostly dry coughs. 



Horses with narrow, shallow chests, weak loins, and long legs 

 are very generally predisposed to cough from very trivial causes. 



