Part 26

The =subcrepitant râle= is another modification holding a place intermediate between the crepitant and the mucous râles. It has been likened to the sound of a moderate effervescence in beer or other liquid. It is referable to the presence of mucus in the smaller bronchial tubes and indicates bronchitis or broncho-pneumonia.

Still other sounds are heard in diseased conditions of the pleuræ. These are =friction sound=, =creaking=, =metallic tinkling=, and =gurgling= or =splashing=.

A =friction sound= is heard in the early stages of pleurisy and is caused by the dryness of the pleural surfaces from the absence of the halitus or vapor which normally moistens them and the deposition of layers of lymph by which the surfaces are rendered rough and uneven. An approximate sound may be observed by placing the palm of the left hand on the right ear and drawing a finger of the right softly over its back. The sound is quick and jerking, one or a few jerks only being heard with each inspiration as the act is cut short on account of the pain attending the friction. It is rarely heard in expiration. It is chiefly heard at the lowest part of the chest where the lungs have the greatest freedom of movement. The thinness of the walls of the chest above the breast bone in cattle and dogs permits the friction sound to be heard more distinctly than in the horse. After the lapse of twelve, twenty-four or forty-eight hours the friction sound disappears, the surfaces of the pleuræ being separated by the liquid effusion, but it may reappear when the fluid is absorbed in the process of recovery. Sometimes the friction is further manifested by vibration of the walls of the chest perceptible to the touch.

The =creaking sound=, as from the bending of a piece of strong leather is caused by the movement of a thick and solid false membrane binding the lungs to the side of the chest. This is often confounded with crepitation.

=Metallic tinkling= is only heard when liquid and gas both exist in the pleural sac and is due to the falling of a drop from the shreds of false membrane above into the fluid contents below. The sound is somewhat like the falling of drops in a closed cask half full of water, or it may be fairly exemplified by placing the palm of the left hand flat on the right ear and striking the back of the hand smartly with the middle finger of the right. The sound is chiefly heard after the patient has changed its position and especially after rising. The explanation of this is that in the recumbent position the liquid changes its place and bathes parts which in standing are surrounded by gaseous products only. Drops accordingly fall into the liquid for some time with diminishing rapidity until they cease altogether. Other explanations of the sound but which less frequently exist are: the ascent of a bubble through the liquid and its bursting on the surface; and the sudden recoil of air from one wall of the plueral cavity to the other as the result of movement or sound generated in the deeper seated solid structures.

A =gurgling= or =splashing= sound is equally indicative of the presence of fluid and gas in the pleural sac. It is almost never heard unless after a sudden movement on the part of the patient causing considerable commotion in the contained liquid. Gurgling sounds transmitted from the abdomen are too often mistaken for this. In small animals with hydro-pneumothorax a quick shaking of the patient will develop it.

=Auscultation of the Cough= is sometimes valuable, though more difficult and less satisfactory in the lower animals than in man, chiefly because of the extensive movement of the ribs in the former. As conveyed through a healthy lung to the ear applied on the side of the chest, the sound is short, dull and indistinct. When the lung is more solid from hepatisation, pleural exudation or other cause, or when the bronchi are dilated the sound is loud and strong. The extent over which it may be heard thus forcibly agrees with the area of lung in a state of consolidation. When a considerable cavity or canal communicates with a bronchial tube and extends to near the surface of the lung the sound is loud and ringing. The note is specially clear and metallic when such a cavity opens into the bronchus by a narrow orifice; an apt illustration of this noise may be obtained by coughing into a narrow necked vessel.

The results obtained by auscultation should be confirmed by percussion before arriving at any definite conclusion as to the state of the chest. Consolidated lung tissue is a much better conductor of sound than the healthy, and sounds conveyed through this may be heard at a considerable distance from their point of origin. Thus the heart sounds are frequently heard over any part of the right side of the chest, and crepitation and other sounds may be heard in the centre of a hepatized portion. On all such occasions the dull sound elicited on percussion will not fail to correct the fallacy.

PALPATION. TOUCH.

This is chiefly useful in cases of pleurisy. As already noticed the vibration of the chest walls which accompanies the early friction sound is sometimes perceptible by the hand applied on the side of the chest. Pressing firmly in the intercostal spaces at the affected part invariably causes wincing and in cattle grunting. Pinching the back in inflammatory chest diseases in cattle but especially in pleurisy has a similar effect.

MENSURATION.

Measurement of the chest gives less reliable results in the lower animals than in man. A cord four feet long should have one end placed on a definite point on the withers and not removed until both sides have been examined. It should be first carried down to a point in the middle of the breast bone and the distance marked by a knot; a comparison may be made by carrying to the same point over the opposite side. It should next be carried successively to the lower end of the 8th rib on the two sides and the difference marked, and lastly from the lower end of the third rib to the lower end of the eighth. These measurements should be made at one stage of the respiratory act, say when the chest is fully dilated, and similar measurements when the chest is collapsed to ascertain any difference in the expansion of the two sides of the chest. In the smaller animals any difference in the expansion of the two sides may be observed by inspection only, the practitioner standing directly behind the animal and watching the movements of the two sides from this standpoint.

A permanent dilatation of one side may be seen in water in the chest confined to one side, and particularly if of some standing. Complete hepatisation of one lung gives a similar result. The intercostal spaces are observed to be wider than usual in such cases, and the movements of the opposite side of the chest are much more extensive than of the affected one.

A collapse with limited movement of one side is an accompaniment of chronic disease of the lung, with wasting of its substance as in cases of tubercular deposit.

DISEASES OF THE LUNGS.

Divisions of lung diseases. Bronchitis, pneumonia, pleurisy, their results, nervous disorders, asthma, hiccough. Œdema. Emphysema. Morbid growths, neoplasms. Infectious and parasitic diseases.

Inflammatory diseases of the respiratory organs situated within the chest may be divided into: inflammation of the air tubes within the substance of the lungs—bronchitis:—inflammation of the spongy tissue of the lung—pneumonia:—inflammation of the covering of the lungs and lining serous membrane of the chest—pleurisy:—and complicated cases in which two or more of these conditions coexist. Beside inflammatory diseases there are the various permanent morbid results of these affections, such as consolidation of lung from exuded products becoming organized; collapse (compression) of lung from organization and contraction of false membranes, thickening or dilatation of bronchial tubes as a result of bronchitis; also nervous affections, such as asthma and hiccough; morbid alterations in the lung tissue independently of inflammation, as pulmonary or pleural œdema and emphysema; specific morbid deposits, as tubercles, glander nodes, cancer, melanosis, etc., and morbid states, due to parasites, as in the verminous affections of cattle, sheep, etc.

BRONCHITIS.

Relation to other maladies of the air passages. Horse. Causes, susceptibility, heat, cold, sudden changes, thick coat, rebreathed air, on shipboard, in zoological gardens, in close stables, in navies, organic matter in expired air, water vapor in expired air, effect on the air and bacteria. Ingesta in bronchia. Medicinal liquids in bronchia in horses and cattle. Exposed locations. Clipping. Smoke and gaseous irritants. Symptoms, in mild cases, in severe: fever, cough in dry stage, after secretion, auscultatory sounds, percussion, discharge, watery, glairy, frothy, later milky, flocculent, purulent. Convalescence. Capillary and pseudo-membranous form. Intensity of symptoms, labored breathing, dyspnœa, violent cough, pinched countenance, dark mucosæ, perspirations, palpitations, asphyxia. Course, duration. Termination, difficult expectoration, blocking of bronchia, pneumonia, bowel susceptibility, skin congestion, laminitis. Chronic condition. Lesions, congestion and contents of bronchia, soft, thick, friable mucosa, absence of vascular ramification, tenacious mucus, false membranes. Collapse, atelectasis, splenisation, emphysema, bronchiectasis. Treatment, in mild cases, in severe, hygienic, steaming, sulphur dioxide, derivatives, guarded laxative, neutral salts, calmatives, expectorants, alkalies, stimulant, oxygen, peroxide of hydrogen, iodide of potassium. Diet. In advanced stages tonics.

Definition. Inflammation of the mucous membrane which lines the bronchia. It is the counterpart of coryza and laryngitis, being but the inflammation of another portion of the same mucous membrane which lines the whole respiratory track. That portion of this mucous membrane which lines the trachea is rarely or never the exclusive seat of inflammation, so that in case of its being implicated we do not speak of the case as one of tracheitis but as laryngitis or bronchitis, according as the throat or bronchia form the seat of active inflammatory action.

The bronchial mucous membrane is often inflamed in influenza, strangles, contagious pleuro-pneumonia of cattle, distemper in dogs, and parasitic diseases of the lungs, but the following remarks will be confined to the simple inflammatory affection. It appears as an acute and a chronic affection.

HORSE. ACUTE BRONCHITIS.

This is more frequent in the horse than in other animals, and especially so in young animals when newly stabled or put in training.

Causes. These are the same as those of catarrh and sore throat. It is but the continuation of the same mucous membrane which is affected in all alike, and the same atmospheric changes, hot stables, noxious inhalations and exposures to cold and wet will induce this disease rather than the others when the bronchial mucous membrane is more predisposed. Bronchitis often supervenes upon sore throat, by the extension of the inflammation downward into the chest. Chilling of the surface by exposure to cold, drenching rains, is a frequent cause, by reason of the intimate sympathy existing between the skin and the mucous membrane. For the same reason certain conditions of the skin will predispose, thus a long, thick coat which keeps the animal constantly drenched with sweat and the skin relaxed and sensitive. Williams draws attention to the frequency and severity of bronchitis in both horses and cattle conveyed by sea during stormy weather, and especially when the hatches had to be fastened down. Such an experience combines in one the evils of an overheated stall, a sudden transition often to extreme cold, a lowering of the vitality of the whole system by the circulation of non-ærated blood, a systemic poisoning by the retention of the waste organic products that would otherwise have been eliminated, and the special weakening of the lung tissue by congestion of the whole pulmonic circulation.

But the development of bronchitis and broncho-pneumonia is the least fatal result. The statistics of our European cattle traffic are rich in the examples of absolute suffocation of cargoes in transit to Europe. The following from Report of U. S. Treasury Cattle Commission is illustrative:

“Dr. Thayer reports the case of a steamer from Boston to Liverpool, with 400 cattle on board, which encountered a storm and came through it with only one animal surviving. Mr. Toffey, of Jersey City, lost 30 head out of a cargo of 300 by suffocation in 1880. This happened, he informs us, on a calm sea on a southern route with a temperature about 90° F., and the wind astern and light so as just to keep pace with the ship. The air on board the ship became perfectly stagnant, and there was no means of establishing an artificial current. A still more disastrous experience befell the steamer Thanemore, Captain Sibthorp, of the William Johnson & Co. line. This vessel left Baltimore with 565 cattle on board, of which 228 perished by suffocation before she reached Cape Henry.”

Among animals that survive such treatment the susceptibility to lung disease including even the contagious forms like tuberculosis is enormously enhanced.

EFFECTS OF MODERATELY VITIATED AIR.