Young animals are kept without food for twenty-four hours and are cast on the side opposite the hernia; they can be placed on the right or left side, or on the back, as seems most convenient. The site of operation is disinfected, and the operation carried out with aseptic precautions. The skin covering the swelling is incised and, the margins of the hernial orifice having been examined, the sac is isolated. Next, an incision is carefully made, any adhesions which may exist are broken down and the herniated parts are reduced. It only remains to suture the wound with silk or catgut, bringing the lips of the fissure together. Finally the skin wound is firmly united, and a large suspensory bandage tightly applied.
If the hernia is of long standing, and is irreducible on account of numerous adhesions, operation may still be attempted. In that case the incision must be an inch or two longer, all adhesions should be destroyed, and the margins of the orifice need to be freshened so as to insure their uniting.
During the days following operation, the animals should have light food, principally gruel, mashes and cooked roots. But it must be borne in mind that this operation is serious, and may possibly be followed by eventration.
DIAPHRAGMATIC HERNIA.
The term diaphragmatic or mediastinal hernia denotes a condition in which certain of the abdominal viscera penetrate into the thoracic cavity. This displacement may be congenital, acquired, or accidental.
The accidental herniæ are of traumatic origin, and are often caused by fractured ribs, which injure the diaphragm. The hernia is then purely diaphragmatic.
Congenital or acquired herniæ are more frequently mediastinal; they occur exactly in the median plane as a consequence of fissure of the diaphragm above the ensiform cartilage, and cause a separation between the two layers of serous membrane enclosing the posterior mediastinum.
The region immediately behind the diaphragm in the ox being occupied by the large viscera—namely, the anterior conical portions of the rumen, the reticulum, the omasum, and the liver—diaphragmatic or mediastinal hernia is far from being common, though occasionally it may be discovered or at least suspected.
Causation. The causes of diaphragmatic and mediastinal hernia are closely connected with injuries in the region of the hypochondrium; with arrest in the development of the diaphragm; or with accidental vertical fissuring consequent on gestation or acute tympanites.
The fissure seems most commonly to occur between the point where the œsophagus passes through the diaphragm and the ensiform cartilage of the sternum, in which case mediastinal herniæ most commonly supervene. As, on the other hand, the rumen, owing to its size, form and position, cannot readily be displaced, the reticulum and omasum are the viscera which most commonly pass into the thorax.