Broken Wind is a disease or unsoundness of the respiratory organs of the horse, which was termed by some old English writers pursiness. The nature of the malady is of a reflex, nervous origin, and appears in the form of difficulty in the act of expiration, the horse making an extraordinary or second effort to expel from the lungs the air which has readily entered them during inspiration.
A broken-winded horse is usually an animal that does not thrive, is lean, and has a dependent belly, the muscles of which are unusually active as expiratory muscles. The characteristic symptoms are best observed when the horse is exercised, the breathing becoming very laboured, the nostrils dilated, the eyes bloodshot, and even blue, showing imperfect purification of blood in the lungs. On watching the chest and flank, the expiratory effort is seen to be double, the animal taking two jerks to expel the air from the lungs. A broken-winded horse has a cough, which is low and hardly heard at a distance of a few yards, and which is usually accompanied by the passage of flatus from the anus. When the animal is oppressed by fast work, or dragging a load up a hill, the pulse is excessively rapid, and the heart beats energetically.
Low-bred horses are liable to broken wind, especially if improperly fed on innutritious and bulky food, and at the same time kept at hard and fast work. It is a dietary disease, and is due to the irritation in the stomach, caused by indigestible food, being reflected from the nerves of the stomach to those of the lungs—in the same way as with ourselves, disease in one tooth seems to set all the other teeth aching. As a matter of fact the nerves of the stomach and lungs have a common origin, and consequently are easily affected one through the other. This indirect irritation causes firstly spasm, and later on relaxation of the little muscles around the air-tubes; consequently too much air gets into the lungs, and causes pressure on the walls of the air-vesicles, terminating in wasting and rupture of them. The result of the destruction of air-vesicles is a lessened area for the aeration of the blood, and is followed by debility and loss of condition. On post-mortem examination we find the stomach much distended with food of a dry nature, and its walls thinned. The lungs are lighter in colour, and float much more buoyantly than in health; little or no blood is seen in them, but they contain a large quantity of air, which makes them crackle when pressed.
The treatment of broken wind is very unsatisfactory; and we can only hope for mitigation of the symptoms by keeping the alimentary canal in proper order, administering occasional purgatives, and feeding on a proper quantity of the best oats, which should always be bruised; also by allowing the horse the best hay in spare quantities—viz. from 10 to 12 lb. daily. We may say that broken wind is incurable; and horses very frequently drop down exhausted when at hard work, and die either from congestion of the lungs, hemorrhage, or simple suffocation.
Broken wind is so bad a form of unsoundness, that horse-dealers sometimes attempt, and even successfully, to hide the defect at the time of the sale, and this they do by causing the animal to swallow shot or grease. A certain portion of lead weighing in the stomach has a wonderful effect in diminishing the symptoms, which become again obvious enough a few hours after the ruse has been practised on some unwary purchaser.