ON ROARING. 
6S 
cause of roaring, and I am inclined to believe that it is a more fre¬ 
quent cause than the transverse bands or coagulated rings. Ob¬ 
serve this specimen. Here is sad ulceration, and considerable 
thickening. Look at this; there is no ulceration, but the mem¬ 
brane is thickened to a very great degree. It is double or treble 
its natural depth. The calibre of the trachea was here materially 
contracted. Look at this third preparation. Here is not so 
much thickenino;, but it is where it can least be borne. It is on 
the membrane covering the chord® vocales. It lessens a passage 
already narrow enough, and it interferes with the requisite freedom 
of motion of these delicate portions of the mechanism of voice. 
If, for ordinary purposes, they can still contract or dilate the 
entrance into the body of the larynx, they cannot sufficiently 
expand the opening when an additional supply of air is requisite 
in extraordinary exertion. It is thus, perhaps, that roaring is 
the occasional consequence of strangles and catarrh, and other 
affections of the superior passages; and even as the result of 
pneumonia, this sensitive membrane is more likely to be in¬ 
flamed and indurated than that which lines the tube of the 
trachea generally. 
Ossification of the Cartilages .—There is scarcely a horse of 
five or six years old who has not a portion of the thyroid cartilage 
ossified: in some cases the greater part of the cartilages are be¬ 
coming bony, or sufficiently so to weaken or destroy their elastic 
power, and consequently to render it impossible for them to be 
freely and fully acted upon by the delicate muscles of the larynx. 
The cartilages no longer freely moving, the air-passages cannot 
vary in size as the circumstances of the animal may sometimes 
require. 
Chronic cough occasionally terminates in roaring. It is as 
likely to be inflammation of the membrane of the larynx as any 
part of the upper respiratory canal; and the membrane cannot 
be subject to chronic inflammation, without that inflammation 
being propagated to the cartilages, the natural consequence of 
which is the deposition of bony matter in them. 
Coughing the Horse .—Some have imagined that the dealers’ 
habit of coughing the horse, i. e. pressing upon the larynx to 
make him cough, in order that they may judge of the state of 
his wind by the sound of the cough, has produced inflammation 
about the larynx, which has terminated or assisted in producing 
roaring. That pain is given to the animal by the rough and 
violent way in which the object is sometimes attempted to be 
accomplished, is evident enough, and this must, in process of 
time, lead to mischief; but I can scarcely think sufficient in¬ 
flammation and subsequent ossification of the cartilages would 
