Part 23

=Labored breathing=, which is at once hurried, deep, and without intermission, is seen in severe laryngitis, croup, capillary bronchitis, and pneumonia, in all cases alike from the difficulty experienced in introducing into the lungs the requisite amount of air. It is especially marked in double pneumonia, pleuro-pneumonia, complicated with effusion in the chest, and in old standing broken wind with dilatation of the right heart.

In all such cases where there is much interference with the æration of blood, whether from obstruction to the circulation of blood or a hindrance to the introduction of air, the horse invariably stands. The fact that he has lain down may be taken as an indication that improvement has taken place. The peculiarity is due to the sharp outline of the horse’s sternum inferiorly so that in lying down he is compelled to rest on his side and the whole weight of the body tends to compress the chest. In the ox, sheep, pig and dog, which can rest on the sternum, breathing can be carried on with comparative ease in the recumbent position, and these animals accordingly do not necessarily stand except in very extensive and violent affections of the chest.

The occurrence of a short inspiration suddenly checked and a prolonged expiration characterizes pleurisy, the check to the inspiratory act being because of the pain caused by dilating the thorax.

The double lifting of the flank in expiration:—the act appearing to be performed by two distinct and successive acts is one of the most prominent symptoms of broken wind, but is not peculiar to this disorder. In the horse it exists in chronic bronchitis, dilatation of the right heart, old standing hydrothorax, and diaphragmatic hernia. It is further frequent in the acute diseases of the chest. In oxen it accompanies pulmonary emphysema, pulmonary consumption, dilatation of the heart, foreign bodies in the heart, and dropsy of the pericardium.

If accompanied by clear resonance over the chest, a permanent wheezing noise heard over the ribs, and the small, weak wheezy cough, it indicates emphysema (broken wind). If with strong impulse of the heart against the ribs behind the elbows, venous pulse in the jugulars, and modification of the second sound of the heart, it bespeaks cardiac dilatation or other heart disease. If with paroxysmal cough, white curdy nasal discharge and harsh rasping sounds heard at the lower part of the trachea or along the upper part of the lungs it betrays chronic bronchitis.

RELATIVE POSITION OF THE LUNGS, HEART AND OTHER ORGANS IN THE DIFFERENT DOMESTIC ANIMALS.

Relative positions of thoracic organs. Diaphragm, heart, lung, in horse, ox, sheep, pig, dog. Palpitation.

The chest is that portion of the trunk closed in on each side by the ribs, above by the bones of the back, below by the breast bone, and behind by the diaphragm. It forms thus a cone flattened from side to side anteriorly, and with its base, represented by the diaphragm which slopes obliquely from above downward and forward and bulges forward in the centre to a greater or less extent according to the plenitude of the stomach and bowels. It results from this arrangement of the diaphragm that a very thin layer of lung only reaches to the posterior part of the chest, and that beneath this are solid and hollow abdominal organs which modify the results of physical examination.

In the =Horse= the anterior third of the chest is covered laterally by the bulky and muscular shoulders so that it cannot be satisfactorily examined. In the median line of the chest, at a point corresponding to the third, fourth, fifth and sixth intercostal spaces, is lodged the heart. It deviates slightly to the left side below and by virtue of a notch in the lower border of the lung is enabled here to reach the surface and its beats may be felt by the hand laid on the side of the chest just behind the left elbow.

In the =Horse= the diaphragm is attached by its outer border to the last rib, and to the lower ends of all the asternal ribs, and the extremity of the breast bone. A thin layer of lung accordingly extends to between the two last ribs superiorly and down to near the lower end of the asternal ribs. The subjacent abdominal organs are arranged as follows:—On the left side, and counting from below, the large intestines (double colon), the stomach and spleen and a portion of the left lobe of the liver:—on the right side, below, the large intestines, above, the liver and pancreas. Of these the stomach and intestines frequently contain gases, while the liver by its solidity gives a special solid character to the right posterior part of the chest. The spleen is too deeply situated to affect much the results of a physical examination. The greatest substance of lung is between the upper and middle thirds of the thorax. The anterior third is inaccessible on account of the shoulders, but more than usual may be reached by raising the fore limb and drawing it forcibly forwards. The space between the third and seventh ribs is occupied by the solid mass of the heart, which especially modifies the result of physical examination on the left side where a notch in the lung allows it to approach the surface.

In the =ox= the diaphragm is only attached to the last rib for two or three inches at its upper extremity; it is fixed to the second last rib as far down as about one-third of its length; thereafter it is attached in succession to the middle third of the third last, to the lower third of the fourth last, to the lower ends of the next two in succession and to the sternum. The result is that the lungs do not extend so far back relatively to the ribs as they do in the horse. They are virtually absent from the last intercostal space, present only in the upper third of the second last, in the upper two-thirds of the third last and reach the lower third only in the space between the ninth and tenth ribs. The paunch alone occupies the space beneath the asternal ribs on the left side, and the liver and the solid mass of the omasum and abomasum that beneath the right. The shoulders in fat improved beef breeds absolutely prevent examination of the anterior third of the chest, though in thin animals and dairy breeds and scrubs more of this may be exposed by raising the fore limb than in the horse. The heart corresponding in position to the third, fourth and fifth intercostal spaces is more completely covered by lung tissue and does not strike the left side so forcibly as in the horse.

In the =sheep= the lung extends to the last intercostal space, nearly as far as its lower end and the heart is covered on the left side as well as on the right by lung tissue. The shoulder is very movable and unless in very fat animals allows of an examination of the greater part of the anterior third of the chest.

In the =pig= fat and indocility combine to defeat our purpose in examination of the chest. If these can be obviated it is well to know that the diaphragm is attached to the upper two-thirds of the last rib, and to the next three in front above their lower third.

In the =dog= the diaphragm is attached to the upper two-thirds of the last rib, to the lower third of the next and to the lower ends of the two following and to the breast bone. The shoulders are so mobile and the breast bone so thin that nearly all the chest may be satisfactorily examined. The heart, covered on both sides by lung, lies nearly horizontally on the breast bone, through which its position and bulk may be clearly made out by percussion.

EXAMINATION BY TOUCH.

Pressure by the fingers in the spaces between the ribs corresponding to the pleura will cause flinching and perhaps grunting in pleurisy. The same result will be seen in pleurodynia. In hepatized lung and pleurisy with adhesions there is a diminished sense of the movement felt in the intercostal spaces of the part in health.

PERCUSSION.

Methods. Tissues as good and bad conductors of sound. Immediate, mediate percussion. Bilateral symmetry and divergence. Effect of building, race, etc. Horse, left side, right. Ox, left side, right. Effect of 1st and 3d stomachs, liver, etc. Sheep, diaphragm, heart. Pig, fat, lean, heart. Dog, method. Birds, back, ribs. In disease, increase, decrease, absence of resonance, in large area, in patches. Crack pot sound.

This consists in striking the walls of the chest so as to bring out the resonance of the parts. In proportion as we tap gently with the tip of the finger or strike forcibly with the closed fist will we elicit the sounds from the superficial or the deeper parts of the lung. Hence slight blows only must be used when the lung tissue is thin, to avoid bringing out the resonance from the deeper seated organs, and both must be resorted to when the lung is thick to ascertain its condition at the various depths. Where a moderate force is requisite the four fingers and thumb of the right hand are brought together in a line and the weight of the hand as moved from the wrist is employed to bring out the sound. The ribs being hard convey sound best from the deeper parts, and on them percussion is usually made. Care should be taken not to mistake the lesser resonance conveyed through the soft tissues of the intercostal spaces for an indication of a diseased condition. In proportion too as the ribs are covered with flesh or fat, the resonance will be diminished and a stronger blow will be necessary to bring out the sound from the lungs.

If the blow is made directly on the side of the chest the percussion is called immediate; if made upon an elastic solid body (pleximeter) laid on the outside of the chest it is mediate. The readiest and perhaps the best pleximeter is the middle finger of the left hand which is to be applied flat upon the side of the chest to receive the blow directed perpendicularly to its surface. In fat or fleshy subjects it should be pressed firmly on the surface so as to compress and condense the soft parts and render them better conductors of sound. Some use flat pieces of ivory, silver, caoutchouc but in employing these the nails of the right hand must be carefully pared, lest by striking the solid body they produce a sound which interferes with the true pulmonary resonance.

In examining the chest the two sides should be compared and if allowance is made for the dulness felt in the lower half immediately behind the left elbow caused by the position of the heart, and the deadness of the sound on the last few ribs on the right side where the liver is situated, any further deviation from a bilateral symmetry of sound is indicative of disease. The general resonance will be decreased by a full stomach which prevents the full inflation of the lungs, and it will be increased if the animal stands on a wooden floor with an empty space below. A short statement of the degrees of resonance over the different parts of the chest in the various races of the domestic animals in a state of health may prove useful.

=Horse.—Left side.= In the upper third the resonance is full behind the shoulder. It diminishes from the 13th rib backward and from the decreasing thickness of lung the blows should become less and less powerful. In this space forcible striking brings out the drum-like resonance of the abdominal organs.

In the middle third the sound over the 5th and 6th ribs is distinct but not full; it increases to the 11th rib and then decreases to the last.

In the lower third a very slight resonance may be observed over the 4th rib.; over the 5th, 6th, and 7th, where the heart approaches the surface the sound is dead; while from this to the 13th rib a slight resonance may be made out.

=Right side.= The upper third resembles that on left side from the shoulder as far back as the 13th rib behind which anything above the gentlest blows brings out a drum-like sound from the large intestine (double colon) especially. This is clear when that is distended with gas.

In the median third the resonance resembles that on the left side. In the lower third it equally corresponds as far as the seventh rib behind, which sound is dull because of the proximity of the liver.

=Ox.—Left side.= The upper third is clear in sound from the eighth to the tenth ribs, and behind this by gentle tapping to the second last (twelfth). Forcible striking, however, brings out the drum-like sound of the upper sac of the paunch which always contains more or less air.

The middle third has a clear resonance as far as the seventh rib; this diminishes to the ninth, behind which it is usually replaced by a dullness due to the presence of food in the anterior part of the paunch. By drawing back the limb percussion may be employed over the first and second ribs as well.