ROARING. 2Gf' 



tliat muscle Lad harder work to displace this viscus in the act of enlarg-in<^- 

 the chest and producing the act of inspiration, and accomplished it more 

 slowlj, and therefoi-e, the air passing more slowly by, the roaring was 

 diminished. We do not dare to calculate what must have been the in- 

 creased labour of the diaphragm in moving the loaded stomach, nor how 

 much sooner the horse must have been exliausted. This did not enter 

 into the owner's reckoning, and probably the application of whip and spur 

 would deprive hun of the means of forming a proper calculation of it. 



Roaring proceeds from obstruction in some portion of the respiratory 

 canal, andoftenest in the larynx, where there is the least room to spare — that 

 cartilaginous box being occupied by the mechanism of the voice : next in 

 frequency it is in the trachea, but, in fact, obstruction anywhere will 

 produce it. Mr. Blaine, quoting from a French journahst, says, that a 

 piece of riband lodged within one of the nasal fossos produced roaring, 

 and that even the displacement of a molar tooth has been the supposed 

 cause of it. Polypi in the nostrils have been accompanied by it. Mr. 

 Sewell found, as an evident cause of roaring, an exostosis between the two 

 first ribs, and pressing upon the trachea ; and Mr. Percivall goes farther, 

 and says that his father repeatedly blistered and fired a horse for bad 

 roaring, and even performed the 02jeration of tracheotomy', and at length 

 the roaring being so loud when the horse was led out of the stable, that it 

 was painful to hear it — the poor animal was destroyed. No thickening 

 of the membrane was found, no disease of the laiynx or trachea ; but the 

 lungs were hepatised throughout the greater part of their substance, and 

 many of the smaller divisions of the bronchi were so compressed, that they 

 were hardly pervious. 



Bands of Goagulated, Lymph. — A frequent cause of roaring is bands of 

 coagulated lymph, morbidly viscid and tenacious, adhering firmly on one 

 side, and by some act of coughing brought into contact with and adhering 

 to the other side, and becoming gradually organised. At other times 

 there have been rings of coagulated lymph adhering to the lining of the 

 trachea, but not organised. In either case they form a mechanical ob- 

 struction, and will account for the roaring noise produced by the air 

 rushing violently through the diminished calibre, in hurried respiration. 

 Thickening of the membrane is a more frequent caiise of roaring than tha 

 transverse bands of coagulated lymph. In many morbid specimens it is 

 double or treble its natural thickness, and covered with manifold ulcer- 

 ations. This is particularly annoying in the upper part of the windpipe, 

 where the passages in their natural state are narrow. Thus it is that 

 roaring is the occasional consequence of strangles and catarrh, and other 

 afi'ections of the superior passages. 



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 becoming 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. 



Chronic cough occasionally terminates in roaring. 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 that is emitted, has produced inflammation about the larynx, 

 which has terminated in roaring, or assisted in producing it. That pain 

 is given to the animal by the rough and violent Avay in which the object is 

 sometimes attempted to be accomplished, is evident enough, and this must, 

 in process of time, lead to mischief; but sufficient inflammation and sub- 

 sequent ossification of the cartilages would scarcely be pi-oduced, to be a 

 cause of roaring:. 



