Treatment. This has long been considered as hopeless, yet preservative and palliative measures are usually accessible, whilst even cures can be effected in certain conditions.
Preventive treatment. First may be noticed the rejection for breeding purposes of all animals possessing those conformations of head, neck and chest already referred to as conducing to disease of the air passages or distortion of the larynx or windpipe. Equally ought all roarers to be set aside unless the exciting cause is accidental such as fractures of the nasal bones, of the trachea, the existence of polypi, etc. Stallions that make a harsh noise in breathing from an accumulation of fat about the throat are not necessarily objectionable.
The employment of the bearing rein so as to compress and distort the larynx is to be avoided. If bearing reins are used in horses having short thick necks and badly set on heads and especially with intermaxillary narrowness they should be passed through rings in the cheek piece of the bridle or between the ears and over the forehead (overdraw check) so that while the head is elevated the nose may be projected forward after the Russian fashion of equitation. This measure has indeed appeared to cure several cases of roaring. I have met with fewer roarers in the same number of horses in America than in England, and this I attribute to the better mode of using the bearing rein on this side of the Atlantic.
The Chick Vetch (Lathyrus Cicera) should be excluded from the fodder of horses or used in small proportion only. In man it is found to be injurious when it forms a twelfth part of the bread used and gives rise to paralysis if it amounts to a third (Aitken).
Palliative and Curative treatment. Medicinal treatment will prove useless in the great majority of cases: as for example in paralysis and degeneration of the muscles, in ossifications, fractures, or distortions of the cartilages, etc., etc. Nevertheless where there is merely thickening of the membrane of the larynx alterative and tonic treatment may be successful especially if associated with iodine ointment or active blisters applied to the throat. A case is reported by Dupuy in which a course of arsenic cured. In these cases as well as in those due to ulceration of the membrane the application of caustic by means of a staff and sponge as advised in laryngitis may prove beneficial. In some cases of this kind the application of the firing iron to the region of the larynx has an excellent effect. Setons have proved useful in some cases.
In cases due to tumors or enlarged glands pressing on the air passages the internal use of iodine and other alteratives and diuretics, and the local applications of iodine, or mercurial ointments or of blisters have been successful. Failing in this the tumors may be removed with the knife when accessible.
If by auscultation the existence and position of a band of lymph can be made out, tracheotomy may be performed and the band excised. Percivall with reason doubts the possibility of the diagnosis.
In cases due to distortion of the larynx from tight reining the bearing reins should be dispensed with or rearranged so as to encourage protrusion of the nose, and the horse should be bitted to the side chains or straps in the stall several hours daily so that the head shall be elevated and the nose protruded.
When roaring depends on paralysis of the laryngeal muscles, a mode of palliation may be adopted as practised by the London omnibus and cab men. A strap is fixed round the nose supported by a strap passing down the middle of the face and the cheek piece of the bridle on each side and buckled beneath the chin. On the inner side of this strap where it passes over the false nostrils is attached on each side a semiovoid pad which presses on the flap of the nostril and regulates the entrance of air. The principle on which it acts will be understood when we consider that the paralyzed cartilage is drawn into the passage by the rush of air and that the closure of the channel is more complete and the roaring more marked in proportion to the force of the current. The pads by lessening and regulating the rush of air into the lungs thus leave the passage in reality more open and largely obviate the difficulty of breathing and the noise.
In extreme cases with the structural lesion in the head, throat, or upper two-thirds of the neck relief may be secured by tracheotomy.