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EXPLANATION OF ROARING IN HORSES Animals -with Heredity Taint of That Disease Are Not Safe for Breeding-. A horse that is a confirmed roarer generally lias, a paralysis of the muscle 3ntrolling the left vocal cord and can be cured only by an operation removing this cord. The paralysis of this muscle that controls the cartilage of the larynx is due to a wasting of the left recurrent nerve, which, if In health, would supply the motor force to the muscle. This force being absent, the muscle loses its power and wastes away. Hence, the left half of the muscle drops down and bars the ingress of the air at each inspiration, which therefore strikes violently against the helpless cartilage; hence, the peculiar noise termed roaring. The cartilage is thus flattened down and expiration is easily effected and therefore is free from noise. When noise is heard, both in breeding in and breathing out, it is due to some obstruction in some part or other of the respiratory passages, usually in the larynx. There are, however, other causes for this complaint. Many roarers have been examined after death and have been found to have no vestige of disease, but some have had the shape of the larynx and upper part of the windpipe materially deformed, crooked and depressed. This has caused inquiry into other causes of roaring, and some probable ones have been found. The parts may have been subject to inflammation and some part of the air tube may have become thickened and inelastic. In this way the inflammation of strangles have been communicated to the larynx or the windpipe, followed by some alteration of structure. Itoaring is no unusual consequence of strangles. A more freqnent cause, and previously unsuspected, is tight reining. More horses have become roarers through painful pressure on these parts by tight reining than is suspected. This is particularly so with drivers, when teaching them to carry themselves well. The arched neck and elevated head of the driver or draft horse is an unnatural position, from which the animal is always anxious to be relieved. Injury always follows when the throat is violently pressed upon and especially when it is exposed to the additional danger from impatience of the animal, through suffering the pain that tight reining causes. The injury is materially increased in cases were the horses head is not well set on, or if the neck is thick, or the Jaws narrow. These physical conformations are peculiarly affected by the tight reining practice. The shape of the larynx or windpipe will occasionally be altered if they be thus squeezed between the jaws and bones of the neck; or if the muscles which expand the opening into the windpipe for the purpose of natural breathing be compressed, they will be incapable of full action, and by degrees will lose the power of action, even when not pressed upon. Therefore, the openinj not being sufficiently enlarged during rapid breathing of the animal, the air will rush violently through the diminished aperture and the sound termed roaring will be produced. A sound somewhat similar to roaring mav also arise from a tumor in the nose. In this case it may be possible to remove it. Or it mav arise from a thickened state of the membrane of the bronchial tubes as sometimes found after catarrh, laryngitis. The usual treatment of this is blistering. Uirge horses with long windpipes arc more predisposed to roaring than smaller ones; ponies are seldom, if ever, affected. The treatment for roaring is unsatisfactorv. If it is occasioned by mechanical injurv as in reining, the remedy is obvious, and this mischief is usually done to young horses and the unthinking horseman is the only cause. Every kind of treatment from firing down the outside of the throat to the excision of the muscle has been done with only partial success. In the early stage of the disease, whether it proceeds from violent pressure or in consequence of catarrh or strangles, or the enlargement of some neighboring part, inflammation will be present; then one can be justified in having recourse to blistering. The blisters may at first be confined to the upper part of the troat, and if unsuccessful there, thev should extend over the whole, length of the windpipe. If the disease arises from paralysis of the muscle controlling the left vocal cord, it can be cured only by an operation removing this cord. Horse breeders, however, should not forget that the roarer, whether horse or mare, will often entail this disease on its progeny. The subject of entailment of disease "by the parent on the offspring, if given more consideration, would eliminate many of the diseases that now affect all livestock on the farm. Therefore, any animal that has the hereditary taint toward roaring in its blood should not hi; chosen for breeding purposes; In buying a horse it is not easy to detect the roarer. Some horses do not even show the symptoms when in moderate exercise. It may, however be easily detected by striking the horse suddenly, or even threatening him with a stick, when he will utter a singular grunt or groan. A roarer is considered an unsound animal, for he is incapable of the exertion which may not only be occasionally but ordinarily required of him. Maritime Farmer.
