Text book of veterinary medicine, Volume 2 (of 5)

by James Law

The respiration furnishes more distinctive symptoms. The breathing which may be hurried and almost panting in colic and acute congestion, is changed in this lesion to a condition of extreme oppression, the nostrils remain widely dilated in expiration as well as inspiration, the angle of the mouth is retracted so as to show the teeth and gums, all the facial muscles stand out, the eyes are protruding and fixed, with dilated pupils, the head is held extended on the neck, and the ribs are not allowed to fall in freely, as after ordinary inspiration, but like the nostrils they remain permanently drawn out. The efforts at inspiration are violent though shallow and marked by lifting of the flanks. There are usually one or two nervous catches in each expiration and sometimes in inspiration as well. This is partly due to the impotence of the deeply lacerated diaphragm as an organ of respiration, but also to the pressure of the displaced and overdistended abdominal organs on the lungs, and to the profound nervous shock. The whole work has been suddenly thrown on the costal muscles, and the depressed nervous system proves unequal to sustaining them in the unwonted toil.

Still clearer indications may be obtained from auscultation and percussion. These are gurgling, rumbling and clucking, or a coarse mucous râle which seem abnormally close to the ear, and a drumlike resonance, much greater than that of emphysematous lung and enormously in excess of what is given out by the sound lung tissue. These may be heard at points where only pulmonary murmurs naturally occur or where abdominal sounds, if heard at all, are distant in health. There may also be areas of abnormal flatness on percussion by reason of the protrusion of a solid viscus like the liver or spleen or one with solid contents. These symptoms are only clear when there is a large intrusion of abdominal organs into the thorax, and they increase rapidly until asphyxia supervenes.

In cases which do not immediately threaten life the extent of the phrenic laceration is usually small and the orifice may be blocked by a bulky organ like the rumen, double colon, stomach or liver, so that any protrusion takes place only to a limited amount and the function of the diaphragm can still be carried on to a reasonable extent. In these cases there may be no very marked symptom at the outset, though the animal is dull, listless and without appetite, or, if he eats or drinks, it is liable to be followed by slight colics and a double action of the flank in expiration as in pulmonary emphysema (heaves). Pressure or percussion in the posterior intercostal spaces is painful. Cough when roused by pinching the larynx is broken and abortive. These symptoms are not distinctive, however, and unless there is a protrusion of a loop of small intestine, to give gurgling and drumlike sounds the diagnosis of the case is liable to fail. The fact of a recent injury may however assist in the recognition of the lesion.

The chronic cases are even more difficult to recognize as there is no record of recent injury and no fever. There may be short wind, the animal breathing hurriedly on slight exertion, and showing a double lift of the flank in expiration (Girard). In place, however, of the tympanitic bowels and frequent passage of flatus which characterize heaves, there is a tendency to colic, especially after meals, and in a certain number of cases there are all the symptoms of fatal strangulation, due to the contraction of the diaphragmatic wound. When the hernia is made by a loop of intestine there are the characteristic symptoms of thoracic gurgling and drumlike resonance.

Cases are on record in which the intestine protrudes through one of the last intercostal spaces or between the ends of the broken rib as a hernia and diagnosis becomes easy by auscultation, palpation and percussion. But in a large proportion of cases the lesion escapes recognition and is only found on post mortem examination.

Lesions. The lacerated orifice in the diaphragm varies much as regards situation, extent, form and the nature of its border. In congenital cases due to an imperfect closure of the natural openings there may be simply a round or ovoid opening, too spacious to be filled by the gullet, vena cava or aorta as the case may be, and capable in the different cases, of containing an organ of any size from the omentum to the liver or stomach. Its margins may be perfectly smooth and even, without any thickening, irregularity, fringe, clot or exudate. In traumatic cases on the other hand the orifice may be of almost any form, size or situation. It may be round, elliptical, triangular, or irregular in many ways. It may be so small as to admit nothing more than a small fold of the omentum, or it may be large enough to open the two cavities, thoracic and abdominal into one common space, and to practically abolish the function of the diaphragm. If the lesion is a recent one the torn margin is irregularly indented or fimbriated and marked by small black blood clots, and somewhat later by exudate and irregular thickening or swelling. When due to a broken rib, the existence of the fracture is patent and the laceration extends along two lines often radiating from point of perforation by the rib. When the laceration has resulted from tympany of the stomach or intestines or from other overdistension of the abdominal organs, the general and comparatively equable pressure has determined the independent laceration of numerous tendinous or muscular bundles all over the diaphragm, so that the divided ends stand out at intervals each bearing its little clot of dark blood, but without actual perforation. The actual orifice in such cases is confined to one point where the tension has been greater or the resistance less. Post mortem lacerations, from tympany or other cause, are easily distinguished from those occurring during life, in that the edges of the wound are pale and bloodless, without clot or exudate.

When the hernia is chronic there is an absence of exposed fringes, and of indications of inflammation, the margins of the orifice being in some cases smooth, even and fibrous, and in others irregularly notched or indented with nodular, fibroid swellings of various sizes at intervals. In such cases the orifice is always relatively small and the hernial mass inconsiderable.

As a rule the peritoneum and pleura, being firmly adherent to the diaphragm, are involved in the laceration so that the hernial mass is not retained in a special sac, but simply protrudes into the pleural cavity, after the manner of an eventration. In exceptional cases they become detached from the muscle, and becoming distended, envelope the hernial mass in a distinct sac.

In hernia with a very small orifice the omentum alone may pass through, even the small intestine proving too large for admission. In such cases it is usual to find the band of omentum adherent to the callus formed by the repair of a fractured rib. When the orifice is somewhat larger a portion of small intestine or of the double colon or cæcum may be engaged, while with a still larger opening the stomach, spleen, or liver may form the hernia. In cattle the reticulum is most likely to be the hernial mass, as noted in an article below. In rare cases the small intestines, omentum or liver protrude (Youatt, Lafosse). The protruding organ is liable to be constricted and strangulated sooner or later by increase in its bulk in connection with its vermicular movements, the accumulation of its contents or the extrication of gas in its lumen, or by the gradual contraction of the orifice in process of healing. Then there may be dark red venous congestion, blood extravasation and effusion, friability and even rupture of the intestinal walls, and adhesions to the wound or the lungs. Once started this congestion and extravasation may extend backward into the abdominal cavity involving a great part of the contiguous intestinal canal.

Prognosis. The worst cases are promptly fatal, while others destroy life in one or two days and such are always to be recognized by the extreme dyspnœa which appears soon after the accident. The slight cases with small orifice and little protrusion may merge into the chronic form, and the animal may even be fit for work, notwithstanding existing dyspnœa, which closely resembles that of chronic emphysema (heaves), but is not benefited by the same treatment. In the ruminants even considerable lacerations and protrusions may not be incompatible with fattening provided the animal is kept from all causes of excitement or over-exertion.