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during inspiration. It is much louder than whistling, but is not of such a 
shrill character. In most. instances, and of these we shall first speak— 
roaring is achronic disease due to wasting and consequent paralysis of 
certain muscles of the larynx, or upper part of the windpipe ; but it may also 
be one of the signs of active inflammation of the larynx itself, in which 
‘case it is merely temporary, and does not constitute permanent unsoundness. 
The origin of the wasting of these particular muscles is not certainly 
known, but we may mention that it more usually attacks those of the left 
‘side only, though it may sometimes involve those of the right side, and that 
it frequently ends in the paralysis of the muscles themselves. Now, as the 
muscles which open the larynx are those which become paralysed and 
unable to act, when the horse takes an inspiration, the characteristic sound 
called roaring is emitted. Roaring is in most instances gradually developed. . 
At first the sound may be intermittent, and even weeks may elapse before it 
recurs after being once heard. As the muscles continue to waste, there is a 
corresponding and permanent loss of power or paralysis, and what at first 
was intermittent becomes established. In most instances, however, the 
noise is not intermittent, but gradually increases in proportion to the waste 
and paralysis of the muscles. The roarer generally emits a very characteristic 
cough in addition to the abnormal sound, and this cough is loud, deep, 
harsh, and dry. Most roarers, moreover, are liable to grunt in addition. 
Hereditary influence’ plays a very prominent part in the transmission of 
roaring, and Professor Williams mentions a breed of horses in which nearly 
all the animals of both sexes are roarers. Horses and geldings are, however, 
more likely to become roarers than mares, which are but rarely so afflicted. 
Small ponies are rarely, if ever, affected with roaring. It has been noticed 
that animals predisposed to roaring in most cases suffer from inflammation 
of the throat from very slight causes, and the disease usually manifests 
itself after several such attacks of sore throat and cold. The long-continued 
use of a tight bearing-rein may induce this complaint, by distorting the 
natural shape of the larynx. Roaring may also be due to tumours or other 
diseases of the nose, or to tumours in the chest cavity, or to injuries or 
distortions of the main air tube, or trachea, as it is termed, or finally to any 
distortion or narrowing of the larynx itself. 
It is said that in India roaring is almost unknown among horses bred 
there, in spite of the fact that many of their imported sires have been 
confirmed roarers, and that this complaint is equally as rare among Arab as 
among Indian horses. Horses also at the Cape are said to be but rarely 
affected. In what direction are we to seek for the explanation of this 
comparative immunity enjoyed by horses in these particular localities? 
There can be but little doubt that the influence at work is more probably 
climatic than dietetic, though both factors may each play their part. There 
is good reason to suppose that hay given in too large amount, especially 
when containing a large proportion of rye grass, is an exciting cause of 
roaring. Cart-horses, moreover, fed on large quantities of dry, hard straw 
and chaff, are probably also rendered more prone to this wasting paralysis ; 
