Читать книгу Special Report on Diseases of the Horse - Charles B. Michener - Страница 95

The thoracic cavity is divided into two lateral compartments, each containing one lung and a part of the heart. Each lung has its separate pleural membrane, or covering. The pleura is the thin, glistening membrane that covers the lung and also completely covers the internal walls of the chest. It is very thin, and to the ordinary observer appears to be part of the lung, which, in fact, it is for all practical purposes. The smooth, shiny surface of the lung, as well as the smooth, shiny surface so familiar on the rib, is the pleura. In health this surface is always moist. A fluid is thrown off by the pleura, which causes the surface to be constantly moist. This is to prevent the effects of friction between the lungs and the walls of the chest and other contiguous parts which come in contact. It must be remembered that the lungs are dilating each time a breath is taken in, and contracting each time a breath of air is expelled. It may be readily seen that if it were not for the moistened state of the surface of the pleura the continual dilatation and contraction and the consequent rubbing of the parts against each other would cause serious friction.

Inflammation of this membrane is called pleurisy. Being so closely united with the lung, it can not always escape participation in the disease when the latter is inflamed. Pleurisy may be due to the same predisposing and exciting causes as mentioned in the beginning of this work as general causes for diseases of the organs of respiration, such as exposure to sudden changes of temperature, confinement in damp stables, etc. It may be caused also by wounds that penetrate the chest, for it must be remembered that such wounds must necessarily pierce the pleura. A fractured rib may involve the pleura. The inflammation following such wounds may be circumscribed; that is, confined to a small area surrounding the wound, or it may spread from the wound and involve a large portion of the pleura. The pleura may be involved secondarily when the heart or its membrane is the primary seat of the disease. It may occur in conjunction with bronchitis, influenza, and other diseases. Diseased growths that interfere with the pleura may induce pleurisy. The most frequent cause of pleurisy is an extension of inflammation from adjacent diseased lung. It is a common complication of pneumonia. Pleurisy will be described here as an independent affection, although it should be remembered that it is very often associated with the foregoing diseases.

The first lesion of pleurisy is overfilling of the blood vessels that ramify in this membrane and dryness of the surface. This is followed by the formation of a coating of coagulated fibrin on the diseased pleura and the transudation of serum which collects in the chest. This serum may contain flakes of fibrin and it may be straw colored or red from an admixture of blood. The quantity of this accumulation may amount to several gallons.

Symptoms.—When the disease exists as an independent affection it is ushered in by a chill, but this is usually overlooked. About the first thing noticed is the disinclination of the animal to move or turn around. When made to do so he grunts or groans with pain. He stands stiff; the ribs are fixed—that is, they move very little in the act of breathing—but the abdomen works more than natural; both the fore feet and elbows may be turned out; during the onset of the attack the animal may be restless and act as if he had a slight colic; he may even lie down, but does not remain long down, for when he finds no relief he soon gets up. After effusion begins these signs of restlessness disappear. Every movement of the chest causes pain; therefore the cough is peculiar; it is short and suppressed and comes as near being no cough as the animal can make it in his desire to suppress it. The breathing is hurried, the mouth is hot, the temperature being elevated from 102° or 103° to 105° F. Symptoms that usually accompany fever are present, such as costiveness, scanty, dark-colored urine, etc. The pulse is frequent, perhaps 70 or more a minute, and is hard and wiry. The legs and ears are cold.

Percussion is of valuable service in this affection. After effusion occurs the sound produced by percussing over the lower part of the chest is dull. By striking different parts one may come to a spot of greater or less extent where the blows cause much pain to be evinced. The animal may grunt or groan every time it is struck. Another method of detecting the affected part is to press the fingers between the ribs, each space in succession, beginning behind the elbow, until a place where the pressure causes more flinching than at any other part is reached. Auscultation is also useful. In the first stage, when the surfaces are dry and rough, one may hear, immediately under the ear, a distinct sound very much like that produced by rubbing two pieces of coarse paper together. No such friction sound occurs when the membrane is healthy, as the natural moisture, heretofore mentioned, prevents the friction. In many cases this friction is so pronounced that it may be felt by placing the hand over the affected part. When the dry stage is succeeded by the exudation of fluid this friction sound disappears. After the effusion into the cavity takes place sometimes there is heard a tinkling or metallic sound, due to dropping of the exudate from above into the collected fluid in the bottom of the cavity, as the collected fluid more of less separates the lung from the chest walls.

Within two or three days the urgent symptoms may abate owing to the exudation of the fluid, and the subsidence of the pain. The fluid may now undergo absorption, and the case may terminate favorably within a week or 10 days.

If the quantity of the effusion is large its own volume retards the process of absorption to a great extent, and consequently convalescence is delayed. In severe cases the pulse becomes more frequent, the breathing more hurried and labored, the flanks work like bellows, the nostrils flap, the eyes stare wildly, the countenance expresses much anxiety, and general signs of dissolution are plain. After a time swellings appear under the chest and abdomen and down the legs. The accumulation in the chest is called hydrothorax, or dropsy of the chest. When this fluid contains pus the case usually proves fatal. The condition of pus within the cavity is called empyema.

Pleurisy may affect only a small area of one side or it may affect both sides. It is oftener confined to the right side.

Treatment.—The instructions in regard to the general management of bronchitis and pneumonia must be adhered to in the treatment of pleurisy. Comfortable quarters, pure air, warm clothing to the body and bandages to the legs, a plentiful supply of pure cold water, the laxative feed, etc., in this case are equally necessary and efficacious. The hot applications applied to the chest, as directed in the treatment of pneumonia, are very beneficial in pleurisy, and should be kept up while the symptoms show the animal to be in pain.

During the first few days, when pain is manifested by restlessness, apply hot packs to the sides diligently. After four or five days, when the symptoms show that the acute stage has somewhat subsided, mustard may be applied as recommended for pneumonia. From the beginning the following drench may be given every six hours, if the horse takes it kindly: Solution of the acetate of ammonia, 3 ounces; spirits of nitrous ether, 1 ounce; bicarbonate of potassium, 3 drams; water, 1 pint.

If the patient becomes debilitated, the stimulants as prescribed for pneumonia should be used according to the same directions. The same attention should be given to the diet. If the animal will partake of the bran mashes, scalded oats, and grass, it is the best; but if he refuses the laxative diet, then he should be tried with different kinds of feed and allowed whichever kind he desires.

In the beginning of the attack, if the pain is severe, causing the animal to lie down or paw, morphin may be given by the mouth in 5-grain doses, or the fluid extract of Cannabis indica may be used in doses of 2 to 4 drams.

If the case is not progressing favorable in ten or twelve days after the beginning of the attack, convalescence is delayed by the fluid in the chest failing to be absorbed. The animal becomes dull and weak and evinces little or no desire for feed. The breathing becomes still more rapid and difficult. An effort must now be made to excite the absorption of the effusion. An application of liniment or mild blister should be rubbed over the lower part of both sides and the bottom of the chest. The following drench may be given three times a day, for seven or eight days, if it is necessary and appears to benefit: Tincture of the perchlorid of iron, 1 ounce; tincture of gentian, 2 ounces; water, 1 pint. Also give 1 dram of iodid of potassium, dissolved in the drinking water, an hour before feeding every night and morning for a week or two.

Hydrothorax is sometimes difficult to overcome by means of the use of medicines alone, when the operation of tapping the chest is performed to allow an escape for the accumulated fluid. The operation is performed with a combined instrument called the trocar and cannula. The puncture is made in the lower part of the chest, in the space between the eighth and ninth ribs. Wounding of the intercostal artery is avoided by inserting the instrument as near as possible to the anterior edge of the rib. If the operation is of benefit, it is only so when performed before the strength is lowered beyond recovery. The operation merely receives a passing notice here, as it is not presumed that the nonprofessional will attempt it, although in the hands of the expert it is attended with little danger or difficulty.

We have described here bronchitis, pneumonia, and pleurisy mainly as they occur as independent diseases, but it should be remembered that they merge into each other and may occur together at one time. While it is true that much more might have been said in regard to the different stages and types of the affections, and also in regard to the treatment of each stage and each particular type, the plan adopted of advising plain, conservative treatment is considered the wisest on account of simplifying as much as possible a subject of which the reader is supposed to know very little.