HEREDITARY DISEASES OP HORSES AND CATTLE. 161 
the most important functions of the body, both animal and 
vital, must be presumed to take place.”* 
The Diseases of the Respiratory Organs will afford some in- 
teresting examples, both in horses and cattle. 
(d.) Roaring . — So called from a peculiar sound uttered by 
the horse when his respiratory actions are violently exc ited. 
Mechanical injury to the larynx, and the windpipe just, 
beneath it, arising from improper use of the bearing-rein — or 
tight-reining, so commonly practised in the breaking of young 
horses — are frequent causes. Sometimes this disease makes 
its appearance independent of any of those uncalled-for 
mischievous acts — such as the result of catarrh, or some sub- 
acute inflammatory affection, causing a thickening of the 
lining membrane of the upper portion of the windpipe ; and, 
at other times, roaring is produced without any apparent cause 
whatever; in which case the disease is attributable to atrophy 
of the muscles of the larynx. 
Without further considering the causes of roaring, this fact 
is clear and evident enough, that its hereditary character is 
very frequently exhibited. Instances are numerous every- 
where of stallions affected in this manner, causing the same 
in their offspring. Mr. Simonds, in his lecture to the 
members of the Royal Agricultural Society at York, referred 
to the circumstance of the larger proportion of roarers found 
amongst the Yorkshire horses, which he attributed to here- 
ditary predisposition ; and we had an opportunity, in conse- 
quence of an official appointment as Judge of the horses at 
that meeting, of proving the truth of this assertion. 
( e ) Broken Wind is another example of diseased action 
derived from abnormal structure, and transmissible by descent. 
This is a disease perhaps not generally considered as having 
an hereditary origin. It is caused by disordered functions of 
the lungs, and is common to horses of sluggish temperaments 
and slow action ; also to carriage and hackney horses, whose 
work is irregular, and, from mismanagement, their exercise 
not sufficiently attended to. On the contrary, it is seldom 
or never seen in the racing stable, and rarely in the hunting 
stable, where the work or exercise, and feeding department, are 
properly conducted. Why is this? Because the condition 
necessary to preserve the healthy functions of the lungs are 
fulfilled in the latter instance, and not in the former. One 
of the chief conditions necessary to this end is exercise. It 
is this only which will promote perfectly free expansion of 
the chest, so that the air may have free and frequent access 
to the air-cells ; by which not only the muscular functions of 
* Medical Notes and Reflections/ by Henry Holland, M.D., F.R.S., &c. 
xxviii. 21 
