374 
RESPIRATION. 
observation and attention, that such cases are discoverable. This 
change of character which is observable in the animal’s breath- 
ing consists of an inequality or disproportion between the in- 
spiration and expiration, the former having increased in extent 
is comparatively prolonged, and the laryngeal murmur has, at 
the same time, lost much of its softness, and become sharp and 
shrill to a certain degree, or, in a very slight quality, sonorous. 
Hoi ■ses that have the laryngeal murmur shrill become whistlers as 
the change in respiration advances. Those in which the quality 
of the murmur is sonorous become roarers. 
There are more horses labouring under this preliminary respi- 
ration to roaring than is commonly supposed; and, as is often 
the circumstance, when lost sight of for a time, they are found by 
their owners or attendants to have become whistlers or roarers. 
Such being turned out for a summer’s run at grass, on coming 
again into work, the disease is so far developed as to leave no 
doubt upon the matter to an ordinary judge; and the cause of the 
disease is attributed by the parties to the turning the horse out, but 
which, in fact, had no share whatever in the affair. 
Topical inflammation of the larynx of an acute kind will fre- 
quently produce a roaring inspiration in twenty-four hours; and 
although, on resolution of the disease taking place, no ill conse- 
quences remain, it so frequently happens that whistling or roaring 
is the result, that great and considerable apprehension of such 
effects are entertained by most practitioners. But few veterinary 
surgeons, I imagine, would feel the same anxiety as to bronchitis 
or simple catarrh terminating in whistling or roaring , because 
such effects are rarely observed ; indeed, active inflammation of 
the mucous surfaces of the trachea and bronchi is not accom- 
panied by any manifest painful hoarse sound in respiration, so 
common in laryngitis. These are important facts relative to the 
seat of roaring. The hoarse roaring sound in laryngitis princi- 
pally arises, in my opinion, from a partial closing of the glottis by 
the epiglottis — nature’s attempt at relief from acute pain by ex- 
clusion of the cold atmospheric air in inspiration ; also from a 
comparison of the sounds produced by laryngeal inflammation 
and the sonorous ejaculation of the confirmed roarer , I am forci- 
bly impressed with the belief of this partial shutting down of the 
epiglottis as a principal cause of the sound uttered by roarers in 
aggravated cases. 
There are instances of horses that were loud sonorous roarers 
presenting no satisfactory lesion on dissection for the malady. 
Such were probably of the above class, from a loss of nervous in- 
fluence in those laryngeal muscles particularly concerned in main- 
taining the proper degree of dilatation of the aperture, viz., the 
