Chapter VII: Part 7

The less urgent cases may be treated by application of cold water or ice to the throat, and the injection of solutions of chloride of iron or alum into the fauces. Or the throat may be painted with tincture of iodine and rubbed with the palm to favor distribution and absorption of the exudate. In dogs the mouth may be opened widely and the dropsical membrane pricked at intervals to drain off the liquid. In the most acute cases the prompt adoption of tracheotomy is the only means of saving life.

LARYNGEAL HYPERÆSTHESIA. CONVULSIVE COUGH.

Convulsive cough with visible lesions—without. Excitants, cold air, or
water, rough or dusty food, irritant agents inhaled or swallowed.
Treatment, hygienic, nerve sedative, expectorant, tonics, Muriate of
ammonia, Sulphur dioxide, silver solution, ferric chloride, alum,
derivatives, elimination, aromatic, dietetic.

The chronic or paroxysmal cough may often be traced to the presence of tumor, ulcer, local inflammation, or parasite, but in some instances no local trouble is recognizable, the general health remains good, and yet the throat is abnormally sensitive and a cough or fit of coughing may be roused by passing into the cold air from a warm stable, by cold water in drinking, by inhaling irritant gas, by the passage of rough or fibrous food, or by handling the larnyx. There is undoubtedly a hyperæsthesia of the larnyx and the horse and dog as being more exposed to severe demands on the physical and nervous systems are especially liable to suffer.

_Treatment_ must be adapted to the conditions. Over-work, damp unhealthy buildings, and all appreciable health depressing causes must be corrected, and a course of iron and nux vomica may be tried. Borax, bromide of potassium, and extract of hyoscyamus, made into an electuary with molasses or honey may be smeared upon the molars four or five times a day. In obstinate cases the inhalation of the fumes of burning salammoniac or sulphur, or the direct application to the larnyx of dilute solutions of silver nitrate, ferric chloride, or alum may benefit. The throat may be blistered by cantharides or mustard. Care should be taken to keep the functions of bowels and kidneys normally active, to protect the patient against cold and damp, and to give nutritive but non-stimulating and easily digested food, as for the horse, bran mashes, roots, grass or scalded hay, and for the dog pulped flesh, soup and mush. Sometimes benefit can be obtained from the vegetable aromatics and stimulants as eucalyptol, tar, turpentine, balsams of Tolu and Peru, tincture of anise, fennel, etc.

INFECTIOUS DISEASES OF THE THROAT.

Infectious throat diseases. Parasites, Leeches. Œstrus larva. Chronic
sore throat. Mechanical removal.

Infections are in many respects the most serious affections of this region but their consideration must be sought under strangles, distemper, diphtheria, anthrax, actinomycosis, tuberculosis, glanders, etc.

PARASITES OF THE THROAT.

=Leeches.= These taken in with the water will sometimes fasten themselves on the walls of the pharnyx or even on the lips of the larnyx, producing cough, sore throat, difficulty of swallowing, bleeding from the nose (or mouth), or dyspnœa. They are to be removed as recommended above under parasites of the nasal chambers.

=Œstrus Larva.= =Bots.= In horses and mules the larva of the œstrus sometimes attaches itself to the mucous membrane of the pharynx or even of the larynx producing chronic irritation, cough and even dyspnœa. A chronic sore throat with nasal discharge, occurring in autumn or winter, in the absence of fever or constitutional disorder may be found to depend on these parasites and to recover when these have been removed by the hand.

GUTTUROMYCOSIS OF SOLIPEDES.

Aspergillus. Complications, ulceration, lesions of adjoining parts,
food in lungs, hepatization, gangrene. Treatment, by incision, sulphur
dioxide, iodine.

Rivolta and Bassi have found in the guttural pouches of horses and a mule, an advancing ulceration of the mucosa partially covered with crusts composed largely of the mycelium, conidia and spores of Aspergillus or a closely allied fungus. In the mule the ulcer had opened into the carotid artery causing a profuse epistaxis. In the three horses there was dysphagia, and the food, descending to the lungs, had caused pulmonary hepatization and gangrene. The description of the ulcers led Raillet to infer the existence of glanders and that the presence of the aspergillus was accidental, rather than a causative factor. In parallel cases the opening of the guttural pouch and injection with sulphurous acid solution or dilute solution of iodine would be appropriate treatment.

DISEASES OF THE CHEST.

Cough, its artificial production, precautions, character in different
animals. Cough in disease, strong, full, ringing, weak, short, broken,
abortive, dry, rasping, croupy, small, husky, soft, humid, rattling,
mucous, paroxysmal, sympathetic, wheezing, roaring, whistling, grunt,
moan. Expectoration, nasal in horse, also buccal in other animals.
Morbid expectoration, watery, viscid, cloudy, flocculent, purulent,
rusty, cretaceous, parasitic, fœtid, varicolored, microbic. Expired
air, warm, cool, vegetable odor, acid, fœtid, heavy. Respiration,
number in health, alteration in disease, rapid, slow, tardy, short,
catching, quick, deep, labored. Position, standing, lying. Pleuritic
breathing, broken winded.

Before describing specific diseases, it is needful to consider the methods of physical diagnosis which enable the practitioner to differentiate the diseases of the chest. Some of the following remarks will bear equally on diseases of the nose and throat as well.

COUGH.

The cough so varied in health and in disease deserves careful practical study. It can usually be excited in solipedes, sheep and dogs by pinching the first ring of the windpipe between the thumb and first two fingers. In oxen it is best produced by compressing the anterior part of the larynx. In old cattle it is difficult to produce coughing. In no animal should the attempt be made rudely nor unnecessarily repeated, as it may tend to excite or to aggravate already existing sore throat.

The cough of the healthy _horse_ is _sharp_, _loud_ and _ringing_, often repeated two or three times and followed by a snort (clearing of himself). It is weaker in young horses and shorter and drier in the aged.

The usual cough of the _ox_ is _weak_, _dry_, _slightly husky_ and _prolonged_.

That of the _sheep_, _small_, _weak_ and _dry_.

That of the _dog_, also weak and dry.

A =strong, full, deep, ringing cough= is rarely heard in disease except in slight irritation of the larynx. In such cases the larynx is tender and slight handling or pinching develops the cough.

A =weak cough= wanting in resonance and heard only at a short distance from the horse, is usually associated with chronic chest diseases and the last stages of acute thoracic inflammations.

A =short=, =broken= or =abortive cough= is one which appears to be suddenly cut short and suppressed, from the pain it causes. It is seen in the early stages of inflammations of the serous membranes of the chest or abdomen, when the quick rubbing of the dry and inflamed surfaces of these membranes on each other produces exquisite pain. It characterizes especially the _debut_ of pleurisy, pleuro-pneumonia and peritonitis. This cough is infrequent for the same reason that it is short.

A =dry=, =loud=, =rasping=, or =croupous cough= is peculiar to the early stages of laryngitis, tracheitis and bronchitis, when the membrane is swollen, tense and dry. It is equally met with in diphtheritic and croupous affections implicating the larynx.

A =small=, =weak=, =dry=, =husky cough= without any _rasping_ is characteristic of broken wind (heaves) emphysema of the lungs, asthma, or chronic bronchitis.

A =soft=, =humid= or =rattling cough= exists in the advanced stages of laryngitis, bronchitis and pneumonia when the activity of the inflammation has given way and a free exudation has taken place from the mucous membrane. It is usually accompanied by a discharge, in solipedes from the nose, and in other animals from nose and mouth.

A =soft cough= with a peculiar gurgling in the larynx is sometimes met with in croup.

A =paroxysmal cough= is one repeated five, ten, or twenty times in rapid succession. It is common in chronic bronchitis, early heaves, emphysema, verminous bronchitis and influenza. In such cases it is observed chiefly when the subject is brought out to the cold air, when he takes a drink of cold water, or when he has just had some active exertion, or some dusty or fibrous food.

A =symptomatic cough= is one due to disease in some other organs than the respiratory, and which irritates the air passages through nervous sympathy (reflex action). It is commonly small, short and dry. Inflammation or other disease of the liver, indigestions and intestinal worms are occasional causes of symptomatic cough. In the case of worms it may be loud, clear and ringing.

OTHER MORBID SOUNDS.

Besides cough may be noticed the _wheezing_ breathing characteristic of _broken wind_, _chronic bronchitis_ and _asthma_, _roaring_, _whistling_, etc., as already described, and the sound between a _moan_ and _grunt_, produced in pneumonia especially in the ox.

EXPECTORATION.

This escapes almost exclusively by the nose in horses, because of the length of the soft palate. It may come from the mouth of other animals, especially when they cough. In the ox the discharge from the nose is rarely seen because of his licking it out with his tongue. Rattles (râles) in the larynx, trachea or bronchia, enable us to ascertain the source of such discharges.

The nasal discharge in acute catarrh, laryngitis or bronchitis, is thin, clear, and slightly viscid, becoming thick, whitish and flocculent as the disease advances. It is yellowish, thick, flocculent and intermixed with shreds of false membranes in diphtheria or in the croup of young foals and calves. It is clear, slightly viscid and watery at the onset of bronchitis. At the debut of pneumonia it is often reddish (rusty). It is bright, red, frothy and bloody in hæmoptysis. It is scanty, clear, watery, and containing minute white flocculi in pulmonary emphysema (broken wind). It is white, thick, curdy, and devoid of viscidity in chronic bronchitis or when a pulmonary abscess is being emptied. It is grayish, thick and flocculent in advanced pneumonia in the horse.

Cows in the advanced stages of pulmonary tuberculosis expectorate a yellowish, sticky matter containing minute hard masses often cretaceous. Calves and lambs suffering from strongyli in the lungs expel these in little pellets in the midst of a thick white material.

The expectoration is fetid, dark red and grumous in gangrene of the lungs.

In pulmonary tuberculosis and glanders the expectoration usually contains the respective bacilli.

CHARACTER OF THE EXPIRED AIR.

The breath is sensibly warmer in excited breathing, high fever, and acute bronchitis and pneumonia. It is cool in most chronic diseases, in advanced consumption and hydrothorax. Its odor is vegetable and acid in the acute indigestions of cattle, and fetid in many chronic diseases of the air passages attended with destruction of tissue, or the escape of imprisoned pus, but especially fetid in gangrenous sore throat or gangrene of the lung.

MODIFICATION OF THE RESPIRATION.

The number of respirations in a given time may afford valuable indications in the horse but in the other domestic animals variation in number imports little. In the ox for instance, the respirations in health may vary from twelve to eighty per minute, according to the heat of the cowhouse, the plentitude of the abdominal organs and other circumstances. So in the sheep and dog slight causes, quite compatible with health, may cause the breathing to become short, panting and hurried.

The young horse breathes ten to twelve times per minute, the adult animal nine to ten. Any excitement accelerates. A horse walked a few hundred yards had the respirations increased from ten to twenty-eight per minute; after trotting five minutes they numbered fifty-two; after galloping five minutes sixty-five.

=Hurried breathing= occurring independently of exercise, heat of the atmosphere, or distension of the abdomen, is indicative of fever, especially if associated with rapid pulse and increased heat of the body.

Infrequent respiration appears in certain brain diseases in the intervals between the more violent paroxysms, also in poisoning by opium and other narcotics. =Tardy or slow respirations= differ from those last noticed in the act occupying a longer time. In infrequent breathing the act may be short, though there are few respirations in the minute. This is likewise seen in brain diseases and sometimes in broken wind. In the last case there is =double action of the flank=, each act of expiration being effected by two successive and distinct elevations of the flank.

=Quick breathing= in which the act occupies only a short time is usually abruptly cut off, the inspiration terminating by a catch or jerk. It is significant of the early stage of pleurisy, and arises from the desire to avoid the pain attendant on the rubbing together of the inflamed surfaces during deep inspirations. It is further seen in tetanus, peritonitis, pericarditis and pleurodynia.

=Deep breathing= with great lifting of the flanks and loins is characteristic of water in the chest, and consequent inability to inflate the lungs.

=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.

In the lower third the first two ribs can be examined and a clear sound should be educed. On the fourth, fifth and sixth ribs there is a full resonance, the heart being here covered by lung tissue, contrary to the condition in the horse. From the seventh the sound becomes duller and the dead sound from the food in the rumen characterizes the lower fourth of the ninth rib.

=Right side.= From the shoulder the resonance gradually decreases in the upper third to the eleventh rib, beyond which the sounds obtained are only from abdominal organs. In the middle third considerable resonance is met with over the first and second ribs, it is very full and clear over the fifth, sixth and seventh, whence it decreases and is quite lost behind the tenth. In the lower third a clear sound can be elicited over the first, second, fourth, fifth and sixth ribs; this is lessened over the seventh and eighth, and completely lost behind the ninth. Any but the slightest blows over these three last ribs brings out the dull, solid sound from the liver.

A very full paunch greatly increases the anterior convexity of the diaphragm, and compresses the lungs into the anterior part of the chest. If the contents of the rumen are solid the resulting dullness on percussion might be mistakenly supposed to indicate consolidation of the lung. This source of error must be carefully guarded against.

=Sheep.= Percussion in the sheep differs from that in the ox chiefly in the following particulars: The diaphragm being attached to the last rib as in the horse, the diminishing resonance of the lung may be traced as far back as in that animal. Thus a pulmonary sound can be obtained in the upper third as far as the last intercostal space, in the middle as far as the second last, and in the lower as far as the fourth from the last. Over the lower part of the fifth and sixth ribs on the left side the resonance is remarkably clear owing to the great relative thickness of the anterior lobe of the left lung which here covers the heart.

=Pigs.= In fat pigs the results are almost negative. In lean animals the middle third on each side gives out a clear resonance behind the shoulder as far as the seventh rib, from which it diminishes to the second last (thirteenth). The sound is less clear in the upper and lower thirds. On the fifth intercostal space below, and on the left side the sound is dull owing to the exposure of the heart through a slight notch in the lung.

=Dog.= Percussion is very satisfactory in this animal because of the amplitude of the chest, the thinness of its walls and the small bulk of the abdominal organs. In the upper and middle thirds on both sides alike the sound is clear and full as far back as the seventh rib, whence it decreases to the last. In the lower third a distinct but moderate sound marks the first eight ribs and is equally clear on the right and left sides. The thinness of the lung in its posterior part demands that percussion be effected by the middle finger only, without any movement of the hand. Unless the dog is very fat, good results may be obtained by percussion over the first and second ribs, the shoulder blade and breastbone.

=Birds.= In these and especially in the webfooted (ducks, geese) the sternum is so thickly covered by flesh that no result can there be obtained. Beneath the wings, however, and upon the back percussion through the medium of a small coin as a pleximeter and with the middle finger alone, is valuable. Beneath the wing a clear sound may be drawn out over nearly all the ribs and on the back over a less extent (two and a half to four inches, according to size).

PERCUSSION IN DISEASE.

=Increase= of resonance without any perceptible modification in character is usually partial and depends on the increased distension of the air cells of one lung, or part of a lung, to make up for the loss of a part or a whole lung through hepatization or pressure by false membrane or from water in the chest. If a part of a lung is solid and impervious it gives a dull, dead sound, contrasting strongly with the increased clearness of the remainder. So with water in the chest, the clearness of the upper parts contrasts unmistakably with the dullness of the lower. By watching the advance or retirement of these symptoms the solidification of a lung and its process of clearing up, and the effusion of water in the chest and its removal may be equally traced through all these stages.

If the increased clearness is confined to the upper, lower, or posterior border of one or both lungs, the sound being natural over all other parts, it indicates the existence of emphysema of the lungs, a condition almost constant in broken winded horses.

If the sound is drum-like over most of the lung it is due either to extensive emphysema or to the presence of air as well as liquid in the cavity of the chest. In the case first noticed there will be the double action of the flank, the weak, dry, husky cough and the wheezing breathing; in the last there will have been the previous attack of pleurisy, and the application of the ear to the chest will detect a splashing sound constant or heard only at intervals or on rising. This should be carefully distinguished from abdominal gurgling.

=Diminished= resonance, noticed over an entire lung, may be due to congestion or œdema of the lung, to the formation of a thick false membrane over the inner surface of the ribs or to a false membrane enveloping the lung and preventing its due distension. Congestion will be distinguished by the blueness of the mucous membranes and the presence of a crepitant sound heard on auscultation. Pleurisy is known by the tenderness on percussion or on pinching the intercostal spaces, and by the presence in many cases of a friction sound. The sound may be further lessened in cattle by the deposit of tubercle on the inner side of the ribs, or the extensive deposition of miliary tubercle throughout the substance of the lung.

=Absence= of resonance, the sound brought out by percussion being similar to that obtained by practising it over the muscular masses of the haunch, is always partial. It is due either to hepatization or to water in the chest. Hepatization is distinguished by its rarely affecting the lower thirds of both lungs at once, by the presence of a crepitating râle round the margin of the area of dullness, and by the increased resonance and respiratory murmur over the sound parts of the same and the opposite lung. In water in the chest on the other hand a friction sound and much tenderness precedes the dullness; the tenderness continues and the dullness reaches the same height on both sides of the chest, in the case of the horse. In the ox, water may exist on one side of the chest only, but the tenderness on pressure and the absence of any crepitation serve to distinguish the case from pneumonia. In the smaller animals the position of the dulness may be altered by turning the patient on its back as the water always gravitates to the lowest point.

The presence of extensive deposits of tubercle, of cretaceous material in tubercular cows and sheep, and the presence of large cysts in the lung may give rise to dullness over a circumscribed area. Such areas of dullness are usually multiple with sound lung between.

A further modification known as the =cracked pot sound= is sometimes heard in horses and cattle. It may be aptly represented by laying the palms of the two hands together in such a way that they meet all round and leave an interval filled with air right in the centre. The back of the one hand is then struck against the knee when the noise of the air escaping gives the characteristic sound. It occurs in consumption or in the advanced stages of inflamed lungs when a large tubercle or abscess has burst into a bronchial tube and the resulting cavity opens into this tube by a narrow orifice.

AUSCULTATION.

Mediate and immediate auscultation. Methods, quiet, normal chest
sounds, tubal, bronchial, vesicular, respiratory, cardiac. Juvenile
respiratory murmur. Horse, left side, right. Ox, left side, right.
Accidental sounds, rumbling, gurgling, crepitation, friction. Sheep,
special features. Goat, force. Pig, Dog, Birds, morbid chest sounds.
Increase, general, partial. Decrease, general, partial. Absence.
Bronchial sound in excess, in improper place. Cavernous, amphoric,
mucous sounds. Râles, sonorous, sibilant, mucous, submucous,
crepitant, subcrepitant. Creaking, metallic, tinkling, gurgling,
splashing, friction. Timbre of Cough. Palpitation. Mensuration.

This is a term used in medicine to denote the mode of exploring an organ by applying the ear over the region in which it is situated and deducing the healthy or diseased condition by the sounds heard. First employed by Lænnec in human medicine it was quickly availed of for the lower animals by Delafond and Leblanc.

Auscultation is =mediate= or =immediate=. =Immediate Auscultation= is practised by applying the ear directly upon the skin, either bare or covered with a handkerchief. In =Mediate Auscultation= an instrument called a stethoscope is employed to convey the sound from the surface of the body to the ear of examiner. The common stethoscope is formed of soft wood (cedar or ebony) or of gutta percha, is from five to seven inches long and a quarter of an inch in the bore. The end applied on the skin is widened into a funnel three-fourths of an inch across at the mouth; the opposite end is flattened out to apply to the ear, is about two inches in diameter and has a hole in the centre to convey the sound. A flexible stethoscope is also used either with one or two ear pieces and though less convenient in general than the common variety possesses this advantage when the heart is being examined that it conveys the sound without the impulse of that organ.

In mediate auscultation the ear should be closely applied to the surface, the right ear being used for the left side and the left ear for the right, but a preference should always be exercised in favor of that in which the sense of hearing is most acute. If a handkerchief is used a single fold only must be applied, otherwise the two layers may rub on each other and produce distracting sounds. In mediate auscultation the instrument should be held perpendicularly to the surface, accurately applied alike to the skin and the ear, and pressed firmly on the surface to condense the soft structures beneath the skin and render them more conducting. If held by the hand care must be taken to avoid the slightest movement of the fingers on the stethoscope, and long hairs should be prevented from entering the tube as being likely to produce additional sounds.

Among other points the following must be attended to in auscultation. Avoid a position in which the animal can strike you with its hind limbs. If necessary in irritable or ticklish subjects have one fore leg held up. Select a quiet time and place, early morning or night is usually best. Endeavor to protect the patient from the irritation of insects or the examinations may be fruitless. Never auscultate over a contracting muscle; the sound of muscular contraction will prevent a correct result. If the natural sounds are indistinct increase them by exercise. The smaller animals are examined with the greatest facility standing upon a table or held in the upright posture with the body resting on the thighs or on the hind feet only. Birds can be held by the wings which may be raised and drawn inward towards the median line to expose the back and sides of the chest.

HEALTHY CHEST SOUNDS.

In all healthy animals two distinct sounds are heard over the chest:—the =tubal= or =bronchial= sound, and the =vesicular= or =respiratory murmur=. The =bronchial sound= caused by the air sucking through the larger bronchi is best heard by applying the ear to the breast over the lower end of the windpipe or to the upper third of the chest immediately behind the shoulder. The respiratory murmur is clear and full in the middle third of the chest immediately behind the shoulder. It is louder and more prolonged in inspiration than in expiration and in the right lung than the left especially in cattle and sheep in which the former is more capacious. It is louder in young animals than in old, hence the name of =juvenile= respiration applied by Leblanc. In thin animals it is better heard than in fat ones, the chest walls being thinner, firmer, and more conducting. In animals of a nervous temperament like the English racer it is more distinct than in the Norman, Clydesdale and other heavier breeds. Deep, broad capacious chests emit a stronger sound than such as are shallow, narrow and short. Exercise, fear or any excitement accelerating the respiratory act increases the sound. A full stomach, certain narcotics and other depressing influences lessen it. Other things being equal the sound is lower in cattle and sheep than in other domestic animals.

=Horse.= The ear pressed strongly upon the breast where the windpipe enters detects a strong blowing sound referable to the lower end of the trachea and the bronchi. In young foals a respiratory murmur is heard when the stethoscope is applied in front of the shoulder, the limb being meanwhile drawn backward. A similar murmur may be heard, but less distinctly over the shoulder blade at this age.

=Left Side.= _Behind the shoulder_ in the _upper third_ of the chest the sound is loud and somewhat harsh, the respiratory murmur being here supplemented by the noise of the air rushing through the larger bronchia. From the 13th rib the respiratory sound is alone heard and becomes weaker to the second last (17th).

In the _middle third_ the respiratory murmur is moderately clear from the 4th to the 6th rib, it becomes louder and clearer to the 9th from which its force gradually diminishes and is lost over the 16th. In the _lower third_ over the 4th, 5th, and 6th ribs the respiratory sound is replaced by the sounds of the heart, each beat being distinctly divided into two sounds, the first dull and prolonged, the second short and quick. The respiratory murmur is heard over the 7th and 8th ribs, is weaker on the 9th and lost over the 10th. In the middle and lower thirds but especially towards the posterior part of the chest, abdominal sounds are often heard. They consist chiefly in gurgling or in a noise like that caused by the air rushing into a bottle which has been turned upon its side when full of water. Such sounds are easily distinguishable from those occurring in a diseased chest as they bear no relation to the rhythmical action of breathing.

=Right Side.= In the _upper and middle thirds_ the sounds do not differ from those of the left side. In the _lower third_ the respiratory sound is clear from the 4th to the 7th ribs; from this it decreases and is lost at the 10th.

=Ox.= In very lean cattle the respiratory murmur heard in front of the shoulder and over the scapula is more distinct than in the same region of the horse.

=Left Side.= In the _upper third_ a clear respiratory murmur is heard over the 8th, 9th and 10th ribs but is lost about the 11th. In the _middle third_ the vesicular sound is feeble at the lower margin of the region and immediately behind the shoulder because of the proximity of the base of the heart. Towards the upper margin it is loud and harsh being complicated by the _tubal_ sound. It is full and clear over the 7th rib whence it decreases in force to be lost at the 11th above and the 10th below. In the _lower third_ the double heart beat is alone heard over the lower part of the 4th rib, the respiratory murmur reappears over the 5th and 6th whence it becomes weaker and is lost at the lower and upper margin of the region respectively over the 8th and 9th ribs.

=Right Side.= The sounds of the _upper third_ simply repeat those of the left side. In the _middle third_ the chief difference is the greater clearness and strength of the respiratory and tubal sounds immediately behind the shoulder. In the _lower third_ a moderately strong respiratory murmur is rendered harsh by a tubal sound due to the proximity of the large bronchus going to the anterior lobe of the right lung. The respiratory murmur continues with diminishing force to be lost over the 8th and 9th ribs.

=Accidental but healthy Sounds.= These are more loud and frequent in the ox than in the horse. There is the same irregular rumbling and gurgling especially on the posterior parts of the chest. Gurgling as from a full bottle inverted is often clearly heard over the last six ribs on the left side, and appears due to the passage of liquids between the paunch and honey comb bag. An occasional sound as of water falling into an empty barrel is heard in the same region in cases of slight tympany and after saliva has been swallowed. Rumbling sounds are chiefly heard over the last ribs on the right side where the large and small intestines are situated. The superadded sounds in the ox are those of _crepitation_ and _friction_. The _crepitation_ or fine crackling due to a dryness of the areolar tissue under the skin is frequently present in oxen in average health. A fine _crepitation_ is also heard on the left side from the bursting of myriads of minute bubbles of air generated among the contents of the paunch during the process of digestion. This is especially marked after the animal has fed on green food or potatoes. A loud _friction_ or _rubbing_ sound, which may be imitated by placing the back of one hand upon the ear and rubbing the palm of the opposite hand upon it, is likewise heard over the left side after eating. It is produced by the movements of the paunch during contraction and not being synchronous with the respiratory acts cannot be confounded with the friction sounds of pleurisy to be hereafter noticed.

=Sheep.= The diaphragm being attached to the last rib as in the horse the respiratory murmur may be heard to the second last. The shoulders being more movable than in the ox the anterior part of the chest can be more satisfactorily examined. The vesicular murmur is heard along the whole lower third on the left side though the heart sounds are superadded over the 4th, 5th and 6th ribs. Crepitation from the subcutaneous areolar tissue is rarely heard. Otherwise the sounds of the chest and abdomen correspond to those of the ox.

=Goat.= This animal differs from the sheep mainly in the greater force and clearness of the respiratory murmur.

=Pig.= It seems ridiculous to speak of auscultating the pig, yet he is sometimes thin enough and quiet enough to permit of one obtaining satisfactory results. Gentle treatment and scratching the back and abdomen will often persuade him to be temporarily quiet and docile. The vesicular murmur is very clear in the middle third of the chest on either side, but diminishes gradually on the last six ribs, and disappears on the second last. It is much less intense in the upper and lower thirds. In the posterior part of the chest rumbling and gurgling abdominal sounds are frequent.

=Dog.= The respiratory murmur is very clear over the whole chest. It is most intense along the middle third and becomes less clear on the 4 or 5 last intercostal spaces. The mobility of the shoulder permits an examination of nearly the entire chest. The respiratory murmur may be heard over the entire length of the lower third on the left side though the heart’s sounds are equally heard over the 4th, 5th and 6th ribs. Rumbling and gurgling abdominal sounds are much less frequent than in herbivora and omnivora.

=Birds.= The respiratory murmur is loud, clear and almost harsh on the sides of the thorax, beneath the wings, and considerably softer as heard on the back.

MORBID CHEST SOUNDS.

The close study of the healthy chest sounds upon the living animal is an essential prerequisite to the appreciation of the morbid. The abnormal noises are so varied, merge into each other by such imperceptible degrees, and so coexist and complicate each other that they often prove extremely puzzling to the unpractised ear. It is no more necessary that the musician should educate his ear to appreciate the most delicate gradations of musical notes, than that the auscultator should educate his in the sounds of the healthy and diseased chest. Written instructions are of about equal value in the two cases, they prove auxiliaries in the acquisition of knowledge but they can never supersede the practical study of the chest. A mere theoretical knowledge is too often useless in the presence of the patient.

The abnormal chest sounds are either modifications of those existing in health, or superadded sounds which have no counterpart in the healthy chest.

_Modifications of healthy sounds._ The =vesicular= or =respiratory murmur= may be =increased= or =diminished= in force or it may be entirely =absent=.

=Increase of the respiratory murmur=, is merely an increase in force without any modification in character and resembles _juvenile_ respiration. If increased equally over the entire chest it is =general=, if only in a part it is =partial=. =General increase of the vesicular murmur= is heard after an animal has been submitted to moderate exertion for ten or fifteen minutes. In animals at rest it is heard in active fevers and in the symptomatic fever which attends acute inflammations.

=Partial increase= as for example in one lung only, or in circumscribed parts of both lungs, and especially along their superior borders, is indicative of disease of the lungs or the pleuræ. It testifies to the impermeability to air of some other portion of lung, from congestion, splenisation, hepatisation, plugging of a bronchial tube with tenacious mucous, tubercular deposits, tumors, emphysema, or hydrothorax. (See under these names.) The healthy portion of lung in such cases takes on the function of the whole, and the loud breathing is called =supplementary=.

=Diminution of the respiratory murmur=, like its =increase=, may be =partial= or =general=. =General diminution= is seen in anæmia, in low fevers, in all very prostrate conditions from the mere want of power to dilate the chest; in general emphysema (broken wind, heaves), in general miliary tubercular deposit in the lungs, or in that form in cattle in which the tubercle has been replaced by cretaceous deposits, from the animal’s inability to fully dilate the air cells; in enteritis, peritonitis and metritis the chest is more fully dilated because of the pain attendant on that act, and the breathing being short and quick the murmur is correspondingly low. In certain brain diseases with sluggish respiration the sound is equally feeble.

=Partial diminution of murmur= is more surely indicative of lung disease. It may arise from partial congestion when a supplementary murmur will be observable over other parts of the lungs, and a crepitant râle soon appears in the congested part; from local emphysema in which there is increased resonance in percussing the part; from tubercular or cretaceous deposit, when there will be exaggerated murmur elsewhere, or from bronchitis with blocking up of one or more small bronchial tubes and with louder respiratory sound in other parts.

=Absence of respiratory murmur= may be due to various causes, all of a diseased nature. Hepatisation of lung may be recognized when this condition is found associated with a crepitating râle around the margin of the silent part, and when percussion shows its solidity and want of resonance. Splenisation is associated with absence of respiratory sound and dullness on percussion, but no surrounding crepitation. Absence of sound in water in the chest is confined to the lower part of the chest, keeps the same level and ratio of increase in front and behind, and in the horse on the two sides, and has been preceded by the characteristic catching breathing and the friction sounds of pleurisy. Large tumors and extensive and circumscribed tubercular deposit will give rise to absence of sound over a limited area and plugging up of one or more bronchial tubes will lead to a similar result. Hepatisation of lung and water in the chest are, however, the common causes of loss of respiratory murmur.

The =bronchial or tubal sound= may be increased in pitch and in harshness in two conditions. 1st. In the early stages of bronchitis when the lining mucous membrane of the air passages is dry, thickened and inelastic. 2d. When that portion of lung intervening between one of the larger tubes and the surface of the chest is solid (hepatised) and thus proves a better conductor of sound than in the normal condition.

=Superadded abnormal sounds.= The =bronchial= sounds may be altered in their character so as to become =cavernous=, =amphoric= or =mucous= (rattling). The =cavernous= sound is usually caused by the presence in the lung of the cavity left after the discharge of an abscess or softened tubercle into a bronchial tube. It is thus preceded by cough and white, creamy discharge from the nose. If the discharge is fetid and grumous there has probably been circumscribed gangrene of the lung. An approximation to the sound may be produced by blowing into a widemouthed glass or porcelain vessel. The sound of =amphoric respiration= on the contrary is like that made by blowing into a narrow necked bottle. It is due to a similar cavity with a small orifice or to the existence of pneumothorax communicating by a narrow canal with a bronchial tube. It is rare in the lower animals, but Delafond mentions one case in the horse and two in dogs.

=Râles.= The remaining morbid sounds are known as _râles_, or rattles. They may either be referable to the bronchial tubes or the lung tissue. They are called dry or humid, according as they convey the idea of air drawn through a dry tube or one containing liquid.

The =dry râles= are due to narrowing of the bronchial tubes from the pressure of adjacent tumors, the thickening of the mucous membrane or the deposition on the surface of layers of tenacious mucus. The greater the narrowing the shriller the sound, and hence the distinction of _bronchial râles_ into =sonorous= and =sibilant= (whistling).