Part 31

PULMONARY APOPLEXY. HÆMORRHAGIC INFARCTION.

Different forms. Embolism with infarction. Embolism from arteritis. Rupture of bloodvessel. Changes in color. Symptoms. Repair.

Hæmorrhage into the lungs may be: 1st. Petechial in infectious diseases. 2d. interlobular as from ruptured vessels. 3d. Infarction or apoplexy. Infarction results from embolism of a branch of the pulmonary artery, which may in its turn be due to clots formed in a diseased heart or in the systemic veins and carried to the lungs in the blood stream. It may also result from inflammation of the inner coat of the pulmonary artery. A virtual stasis occurs beyond the embolism, and the blood filtering in through the anastomosing capillaries fills and blackens the affected lobule. With rupture of a considerable vessel the blood escapes en masse and appears like black currant jelly. As it ages it becomes granular and changes to a yellow color, or it may form a necrotic mass enclosed in a cyst as in lung plague. The symptoms, apart from the absence of respiratory murmur and resonance, are not diagnostic. It may take months to undergo liquefaction and absorption. Iodide of potassium, bitters and stimulating diuretics may be given.

PNEUMONITIS; PNEUMONIA; INFLAMMATION OF THE LUNGS.

Definition. Inflammation of the spongy tissue of the lungs uncomplicated by that of the bronchia or pleura.

Divisions. This affection has been variously divided according to seat, nature, and complications: thus:

Single Pneumonia: Affecting one lung: right or left.

Double Pneumonia: Affecting both lungs.

Lobar Pneumonia: Affecting one lobe or by lobes.

Lobular Pneumonia: Affecting by lobules.

Acute Pneumonia: Subacute Pneumonia. Chronic Pneumonia.

Croupous or Fibrinous: With fibrinous exudate.

Catarrhal: With exudate rich in cells and granules.

Hæmorrhagic: With extravasation of blood.

Purulent: Tending to pus: abscess.

Necrotic: Tending to gangrene: sequestra.

Desquamative: With great proliferation of alveolar epithelium.

Interstitial. Interlobular: Affecting mainly the interlobular connective tissue.

Hypostatic: Dependent on gravitation of the blood.

Metastatic: Due to embolism.

Parasitic: Caused by parasites. Due to wounds or foreign bodies.

Contagious and Traumatic Pneumonia.

Many of these are, however, but localizations of the same affection and others are manifestly microbian diseases which in the present state of pathology it is not always easy to early distinguish sufficiently for clinical and therapeutic purposes. For the sake of convenience therefore pneumonia will here be treated of generally, and under the headings devoted to etiology, pathology, therapeutics, etc., attention will be given to distinctions. Those pneumonias that are but pulmonary manifestations of other diseases—influenza, glanders, tuberculosis, strangles, contagious pneumo-enteritis, lung plague, septicæmia, pyæmia, swine plague, hog cholera, petechial fever, actinomycosis, and neoplasms will be considered under these respective headings.

ACUTE CROUPOUS PNEUMONIA. PNEUMONITIS IN THE HORSE.

Definition. Differentiation from acute vascular congestion. Predisposing causes, age, sex, stabling, training, diet, impure air, low health, previous lung disease, plethora, climate, season, exciting causes, chill, fatigue, leucomaines, sudor, draughts, plunging in or spraying with cold water, clipping, inhalation of irritant smoke, gas, dust, drawing of food, irritating or insoluble drugs into the lungs, neoplasms, parasites, contusions, fractured ribs, punctures, contagion, plurality of germs, bacillus of Friedländer, micrococcus of Talamon and Fränkel, diplococcus pneumoniæ equina of Schütz, diplococcus pneumoniæ equina of Cadeac. Symptoms, chill, hyperthermia, dullness on percussion and crepitation in the lower part of the lung, reaction, congested mucosæ, accelerated labored breathing, excited circulation, pulse oppressed, cough deep, patient statant, elbows everted, nose protruded, nostrils dilated, approaching door or window, pinched countenance, skin dry, harsh, adherent, partial sweats, loins insensible, nasal discharge rusty, dependent part of lung largely non-resonant, with peripheral crepitation. Blowing in abnormal situation over hepatized lung. Decubitus, its significance. Course. Results. Favorable indications in pulse, breathing, face, temperature, appetite, decubitus, clearing of lung. Unfavorable indications in breathing, pulse, fever, face, uneasy movements, pawing, cold limbs, prostration, nervousness, weakness. Sabacuto Pneumonia. Terminations of pneumonia, death, resolution, splenisation, abscess, gangrene, red hepatisation, gray hepatisation, fibrinous consolidation. Lesions. Congestion, exudation and cell growth, hepatization—red and gray, deliquescence, abscess. Blood, loss of red globules, increase of white, excess of fibrine, glandular swelling, pleurisy, degenerations in other organs, laminitis, rheumatism. Treatment, adapted to strength of subject and type of disease, hygienic, anti-rigor, antiphlogistic, expectant, stimulant, antipyretic, febrifuge, sedative, moist compresses, derivatives, laxatives. In subacute form tonics, heart stimulants, febrifuge. In chronic cases add rich digestible diet, and easy open air life.

This consists in inflammation of the spongy tissue of the lung involving mainly and primarily the walls of the alveoli and interlobular connective tissue with their respective trophic centres (nuclei). The acute congestion of excessive heart action and debilitated pulmonary capillaries described above, is primarily a disease of the bloodvessels which become over distended and may or may not lead to the inflammatory processes in their walls and the tissues adjacent. Pneumonia on the other hand is essentially inflammation of these tissues and nuclei, with exudation usually of a fibrinous material into their substance.

PREDISPOSING CAUSES. =1.= =Age.= A very early age is nearly exempt, and from 6 years upward there are fewer cases relative to the equine population, variations that may be better accounted for by stabling, training and acquired immunity than by the mere fact of age. Of 237 cases, 2 were 3½ years; 32 were 4 years; 19 were 5 years; 131 were 6 to 11 years; 46 were over 11 years; and 7 of uncertain age (Trasbot). =2.= =Sex.= No visible effect. =3.= =Stabling, training, change of food.= While the young colt at pasture is practically immune, the period of stabling, transition to a dry and grain diet, and to the nervous excitement attendant on training and unwonted work as shown in the statistics of Percivall and Trasbot determine an enormous increase of cases. In a cavalry regiment Percivall found that 56.6 per cent. of all lung diseases occurred before the 5th year, and Trasbot found that at the Alfort Veterinary College 13.5 per cent. of all equine pneumonias occurred in the 4th year. =4.= =Hot Stables.= =Impure Air.= These two conditions usually coexist and prove potent causes especially in young horses brought from the fields. We cannot, however, separate this cause as usually observed from the action of pathogenic germs which are preserved and concentrated in such places. =5.= =Poor Health.= Debilitating diseases, insufficient and poor diet, overwork, exposure to cold draughts or darkness and any other cause which lowers the vitality predisposes. =6.= =A Previous Attack.= This usually leaves some structural or functional change which renders the lung more susceptible to a subsequent invasion. Against this must be placed the immunity which follows the contagious forms, but as this is usually exhausted in the course of six months it does not invalidate the position that the permanent impairment of pulmonary integrity is a predisposing cause. =7.= =Plethora.= Tending as this does to congestion it must be accepted also for the next pathological step—pneumonia. =8.= =Climate and Season.= This is notoriously an important factor. At Paris, Trasbot met with 237 cases in the nine months from October to June inclusive and but 8 cases in the summer months—July, August and September. In Great Britain, where the vicissitudes are less severe Percivall had in the cavalry horses in the seven months from October to April inclusive 146 cases = 20.85 Per month, and in the 5 months from May to September inclusive 62 cases = 12.4 per month.

Exciting Causes. Nearly all the above causes when acting with unusual force may become direct factors in causation. The effect of a sudden and extreme chill is especially to be feared. Even in cases that are unquestionably due to a microbe as the essential cause, the nervous disorder manifested in the chill, and the clogging of the pulmonary circulation in connection with the retrocession of blood from the surface of the body furnishes the opportunity for the colonization of the germ. The average horse at pasture will stand with impunity cold storms of rain, snow, and sleet, and transitions from a warm noonday sun to a cold night wind and dew and even frost, but under other conditions of the system, with the fatigue and fret and sudden changes of food and regimen attendant on domestication, or with any derangement of an important bodily function the chill is often the manifest occasion of disturbance of the balance of health, and the supervention of pneumonia. =Fatigue=, a system charged with =leucomanies=, and a =free perspiration=, which is suddenly checked by exposure, at rest, to a =cold rain=, or =snow=, to a =draught between door and window=, to =immersion in the cold waters= of a river, or to =sponging with cold water= is quite liable to cause pneumonia. An unduly heavy winter coat, an individual peculiarity or determined by a cold environment in autumn often predisposes strongly to such dangerous chills, by the frequency and profuseness of the perspirations and general relaxation of the system. Clipping of such subjects is a true hygienic measure though it entails the need of extra care in blanketing. Again in the animal that has already suffered from disease of the respiratory organs these chills are more dangerous factors.