490 TYPES AND MARKET CLASSES OF LIVE STOCK 



of a severe sore throat. Any obstruction of the free passage 

 of air in some part of the respiratory tract may cause roaring; 

 occasional causes are nasal polypi, thickening of the membrane, 

 pharyngeal polypi, deformed bones, paralysis of the wing of 

 the nostril, etc. However, chronic roaring is caused by paralysis 

 of the muscles of the larynx, thus permitting the cartilage and 

 vocal cord to lean into the tube of the larynx. The noise is 

 made during inspiration, and in far-advanced cases may be 

 produced also during expiration. A horse is tested for roaring 

 by putting him to severe exertion, as the sound is usually made 

 only when at work. Roaring is a serious unsoundness because 

 it incapacitates an animal for severe work, and it is a serious 

 blemish because the noise is unpleasant. It is classed as an 

 hereditary disease. Treatment varies depending on the exact 

 cause, and includes a course of iodide of potassium in the early 

 stages of the disease, or, in advanced cases, operating on the 

 larynx. 



Grunting. When a pass is made at a horse with a stick, 

 or he is otherwise startled, and he grunts, he should be further 

 tested for roaring. It is a common thing for a roarer to grunt, 

 although grunters are not always roarers. Such animals should 

 be given a severe test of wind. Pleurisy and rheumatism will 

 cause grunting, which ceases when the animal recovers from the 

 disease. 



Whistling. This is only a variation of the sound emitted 

 by a roarer. It may be temporary, due to a severe sore throat. 



Sand crack. Sand crack is a splitting of the wall of the 

 hoof, beginning at the coronet, and commonly at the inner or 

 outer quarter in the fore feet or at the toe in hind ones. It is due 

 to imperfection in the growth of horn. It may cause lameness 

 through sensitive parts -being nipped by the crack. It con- 

 stitutes unsoundness. The treatment is rest and cutting a 

 notch transversely below the crack. If there is lameness the 

 crack may be clasped. The shoe may be seated out below the 

 crack, relieving pressure. 



Sidebones. Sidebones are formed by the ossification of 

 the lateral cartilages of the foot, so that they become hard 

 and unyielding, instead of soft and elastic. (See Fig. 115.) This 

 disease is most common in heavy horses. They are found more 

 often in the front feet than in the hind ones, and the outer carti- 

 lage is more often affected than the inner one. In the hind feet 

 they are of little importance, since they cause no lameness. 



