BACTERIOLOGY.
a. Bacillus of Friedländer. This is a short rod with rounded ends, often merely oval, occurring in pairs, or chains of four, and under given circumstances surrounded by a transparent gelatinous capsule. It is ærobic, nonmotile, does not liquefy gelatine, nor sporulate, and in gelatine stick cultures has a nail-like growth. This was found by Friedländer, Frobenius, Weichselbaum and Wolf in the pulmonary alveoli in a small proportion of cases of croupous pneumonia in man. The cultures, injected into the lungs of animals, killed one dog (out of five), six Guinea pigs (out of eleven), and thirty-two mice (all the injected). Lesions were intense congestion of the lungs, seropurulent pleural effusion, and enlarged spleen, while the bacillus swarmed in the blood and exudate.
Micrococcus Pneumoniæ Crouposæ. First found by Sternberg in his own saliva in health, and by Pasteur in the saliva of a rabid child. Afterward found in the great majority of lungs affected with croupous pneumonia in man, by Talamon, Salvioli, Sternberg, Fränkel, Weichselbaum, Netter, Gamalei, etc. Later it was found in meningitis, in ulcerative endocarditis, in arthritis, in otitis media, and in acute abscess in man.
It is a spherical or oval coccus, arranged in pairs, in fours, or exceptionally in eights or tens. Lanceolate forms are the rule in the blood of animals, and circular in artificial cultures. It stains readily in aniline colors and by Gram’s method, grows in ordinary culture media, at 37° C. in the absence of free acid, and in gelatine stick cultures as small, white colonies along the line of culture, without liquefying the gelatine. It dies in ten minutes at 52° C. (Sternberg). Its virulence lessens in artificial cultures, but is restored by passing through the body of a susceptible animal.
Injection into the lungs or trachea of rabbits, mice, sheep and, less certainly, Guinea pigs, produced distinct fibrinous pneumonia filled with the microbe. In dogs, subcutaneously, it caused abscess, but in the lungs an acute fibrinous pneumonia which only exceptionally proved fatal, recovery usually taking place in ten to fifteen days.
Klemperer induced immunity, sometimes lasting six months, by intravenous injection of filtered cultures.
Diplococcus Pneumoniæ Equina. First found by Schütz in the lungs of pneumonic horses in 1887. It is an oval coccus arranged usually in pairs or in threes or fours, and surrounded by a transparent envelope. It stains in aniline colors but not by Gram’s method. It is ærobic and grows in gelatine at ordinary temperature without liquefying it, and in stick cultures forms a line of small, white, separate colonies which do not coalesce by growth. Does not grow on the surface of the gelatine around the puncture. Line cultures on agar are in colonies like minute transparent droplets. In bouillon it develops long chains.
Inoculated on the rabbit, Guinea pig and mouse, it produced death with pneumonic affections (hæmorrhagic congestion or inflammation), but it failed to take in some of the rabbits and Guinea pigs. Chickens and pigs proved immune. Injected into the horse’s lung or as spray into the trachea it produced true croupous pneumonia. Fiedaler and others obtained similar results. Peter has found the fæces of pneumonic horses virulent, an important point in connection with disinfection.
Schütz found that 20 grammes of the culture, in an equal quantity of boiled water, injected into the horse’s trachea, produced a rise of temperature by two or three degrees, with rigors, cough, accelerated pulse, elevated temperature, dyspnœa and prostration, but that this subsided in a few hours. By repeating this every thirty-six hours, the fourth or fifth would fail to produce a reaction and the subject proved immune.
Cadeac’s Diplococcus Pneumoniæ Equina. In the lungs of cases of contagious pleuro-pneumonia of the horse Cadeac found a round noncapsulated coccus appearing in pairs, or rarely in chains, and staining by Gram’s method. It grew slowly in bouillon and agar at 37° C., forming on the latter in twenty-four hours, a thick, whitish, oily drop, which, as it grew larger, assumed a silvery whiteness, and dried in the centre. In bouillon it precipitated a powdery sediment. The reaction of the culture medium was unchanged. It lost virulence rapidly in artificial cultures or by a heat of 50° C., and it died in ten minutes at a temperature of 60° C. Virulence was long retained when dried, or even in putrid material.
This proved infecting to the ass, rabbit and Guinea pig, while the cat and white rat proved immune. Intratracheal injection of the dog produced a transient pneumonia. The ass inoculated with the blood of the infected rabbit died in three days, with a hepatized lung, pleurisy, and swarms of the microbes in the lungs, blood and internal organs. Rabbits injected intravenously had enlarged spleen, reddish exudate in the serous cavities, urine stained with hæmoglobin, and lungs and kidneys congested. With intratracheal injections the lesions were exclusively pulmonary. The pulmonary lesions were less constant in the Guinea pig. Weakened virus caused pulmonary lesions only without septicæmia.
It has been suggested that this coccus is at least closely related to that of pneumo-enteritis of the horse.
Symptoms. The onset of pneumonia is not often seen by the veterinarian, who is called in only after the cough, loss of appetite, hurried breathing and rigor has revealed illness to the attendants. Hence perhaps chill and rise of temperature have been placed among the earliest symptoms. The symptoms are more violent in the racer, trotter and other nervous animals. Trasbot positively claims, that considerable pulmonary inflammation and even exudation have taken place before there is any chill or rise of temperature. This is especially the case in the heavy lymphatic races of draught horses, which often according to this author perform their usual work for days after inflammatory exudation has set in. A fair counterpart of this is found in lung plague of cattle and it would indicate that both start from a local infection, which gradually extends until the systemic derangement is induced. As usually seen, and especially when it follows exposure to severe cold, a staring coat or a shivering fit usher in the disease, the degree of the chill bearing some ratio to the coldness of the air and to the future severity of the malady. This may be accompanied by a small, dry cough, but without any other marked sign of lung disease. With the access of the hot stage the characteristic symptoms of lung disease are manifested, at first resembling those of congested lungs, but less severe than those given under that head. There is a distinct increase of the body temperature; the visible mucous membranes are suffused with a blush; the expired air feels hot upon the hand; the breathing, 30 to 40 per minute, is short and accompanied by much lifting of the flanks—(labored); the cough is deep as if coming from the depth of the chest, but not so hard nor so painful as in bronchitis; the legs are placed apart, the elbows turned out and the head protruded to facilitate breathing; the nose is turned to an open door or window if any such is available; the contraction of the muscles of the face, the dilated nostrils and the retracted angle of the mouth give an anxious expression to the countenance; the eyes are semi-closed; the pulse full but soft—(oppressed)—, beats from 48 to 70 per minute; the bowels are slightly costive, the urine scanty and high colored; the skin inelastic—hidebound—harsh and dry, though sweats may bedew it in parts; the loins insensible to pinching; and if there is any discharge from the nose it consists only in a reddish—rusty—colored mucus.
Auscultation and percussion complete the diagnosis. At the outset the inflamed portion of lung, usually near its lower part, conveys a crepitating sound to the ear, but as consolidation extends the healthy murmur and the crepitating râle are alike suppressed over the whole extent of the hepatised portion around the margin of which a line of crepitation betrays the limit of the advancing inflammation. A similar line of crepitation encircles the hepatised mass even when the exuded products are being absorbed and when the lung is being cleared up and restored to its healthy state. Thus the advance of the inflammation, and the progress of recovery can be equally followed by the crepitation which, in the different circumstances, betokens active inflammation or active absorption. When both lungs are involved the posterior parts are chiefly implicated, while if the pneumonia is single it may attack the anterior, median or posterior part, or the entire lung may become consolidated. If hepatisation exists in the anterior part of the lung the thick fleshy shoulder will forbid any satisfactory examination, but if in the middle portion only, while the respiratory murmur is lost it will be replaced by a strong blowing sound (bronchial respiration) because the noise of the air rushing through the larger bronchial tubes to the posterior healthy part of the lung is conveyed with greater force to the ear through the consolidated lung tissue. This is audible from the lower third of the chest to the upper limit of hepatization. The respiratory murmur in the healthy lung is always louder than is natural.
Percussion confirms these results. Over the hepatised lung where no respiratory sound remains, a dull, dead sound only is brought out by the impulse of the fingers or closed fist, comparable to that obtained by percussion over the muscular masses of the shoulder or haunch, and forming a marked contrast to that obtained over the surrounding healthy lung. There is not that tenderness on pressure in the intercostal spaces which characterises pleurisy, but a sharp blow with the closed fist leads to wincing and usually grunting because of the concussion to which the diseased part is subjected. By increasing the force of such blows the deepest parts of the lungs may be tested, since in this way dullness due to consolidation of the deeper portions of the lungs may be detected even though the superficial investing parts are healthy.
The nature of the symptoms will vary according to the extent and character of the inflammation, from mild febrile reaction, with excited breathing and slight crepitation, to the more severe varieties in which the intensity of the symptoms are such as to threaten suffocation.
A marked feature of pneumonia in solipedes is that the patient obstinately stands in one position and never lies down so long as the severity of the inflammation lasts. The sharp crest on the lower border of his breast bone compels the horse to lie on his side, and since in this position the whole weight of the body has to be overcome in any full dilatation of the chest, he cannot retain the recumbent posture when any serious impediment to breathing exists. Hence it is that the fact of a horse suffering from pneumonia having lain down and remained so for some time is justly accepted as an indication of improvement.
Progress and results of the disease. The general symptoms above noted, remain with more or less intensity throughout. After the first flush of heat, on the occurrence of febrile reaction, the limbs become alternately hot and cold, and in this the general surface partakes to a less extent.
The tendency of pneumonia is to a crisis and recovery. Certain days have been supposed to be critical and on the whole the third, seventh, eleventh and fourteenth are those on which a favorable change is most probable.
Among the more favorable indications are the manifest abatement of the high bodily temperature and febrile symptoms generally, the increasing ease and regularity of the breathing, the greater force, distinctness and slowness of the pulse, the permanent return of warmth to the limbs, the softer and more elastic feeling of the skin, the recovery of appetite, and above all, the turning of the nose from the open window or the retention of the recumbent position for a length of time. These symptoms will become more patent day by day, and the absorption of the effused products and the clearing up of the lung may be traced by the gradually decreasing area of dullness and of the circular line of crepitation as ascertained by percussion and auscultation.
If on the contrary the disease takes an unfavorable turn, some such signs as the following will manifest it: Increasing rapidity and embarrassment of the breathing; smallness and indistinctness of the pulse, which is increased to perhaps 100 beats per minute; tumultuous heart’s action, the impulse of which is strongly felt behind the left elbow; a more laborious working of the flanks; frequent despondent looking toward the flanks; pawing with the fore feet, lying down, and as suddenly rising again; permanent coldness of the extremities; hanging head with great dullness and despondency of expression; dull, sunken, lusterless eye; hanging lower lip; leaden hue of the nasal mucous membrane; convulsive twitching of the muscles of the surface; reeling in gait, and extension of the crepitation over all the still pervious lung.
Subacute Pneumonia. This term is employed to designate that subdued or milder form of the disease which sometimes arises spontaneously and at others follows the acute.
In this variety the characteristic symptoms may be much less marked and the disease is less easily recognized. There is some acceleration and quickness of pulse, lifting of the flanks and heat of the mouth and body generally. There are alternations of heat and cold of the surface and extremities, a rough, unthrifty coat, hidebound, a dull, listless moping manner and the same symptoms on auscultation and percussion as in the acute form.
The changes take place slowly but the disease may prove obstinate and is often followed by permanent alterations in the lungs. Rheumatic affections of the limbs, inflammation of the feet, and other diseases frequently supervene during the course of this form of the affection.
The terminations of pneumonia are:—by death; resolution with absorption of exuded products:—splenisation; abscess; gangrene; permanent consolidation with organization of exuded products. The disease will sometimes lapse into the chronic form.
Death is fortunately the least frequent issue. It may follow on rapidly advancing and general congestion of the lung,—asphyxia; from heart failure, the overworked organ becoming exhausted under the strain of forcing the blood through the virtually impervious lungs; from hyperthermia, the limit of bodily temperature 108°F. having been reached or exceeded; or from collapse and exhaustion.
In resolution which is the most favorable termination the febrile and other symptoms subside and the exudations in the effused lung undergo a process of liquefaction and absorption until neither auscultation, nor percussion nor even the examination of the lung after death will show the slightest trace of the pre-existent disease. This is the most common termination in single pneumonia in the horse.
Splenisation is that condition of lung already described under the head of pulmonary congestion, and if affecting both lungs throughout, necessarily destroys life by arresting the æration of the blood.
Abscess. Diffuse suppuration is very common in the stage of gray hepatization. In this the affected lung becomes more or less extensively infiltrated with pus limited by no distinct membrane like the pus of an abscess, but exuding freely from the cut surface of the lung or escaping from its interstices when it is pressed. It is preceded and in its early stages associated with the formation of granular masses and corpuscles. Its existence cannot be certainly ascertained though it may be surmised when after hepatization of a portion of lung a mucous râle, a sort of gurgling, is heard in the adjacent bronchium and an abundant muco-purulent discharge takes place from the nose. It threatens extensive destruction of lung tissue.
Circumscribed suppuration or abscess is infrequent though occasionally met with in the horse and ox. In this case the excessive exudation at one point liquefies and the surrounding lymph becoming organized into a vascular membrane an abscess is formed. This may burst into the bronchial tubes and be discharged by the nose. In less favorable cases it makes its way toward the pleural surface and opens into the cavity of the chest. It is impossible to detect the existence of a pulmonary abscess though after it has burst into a bronchial tube the existence of the cavity may be ascertained by the amphoric sound heard on auscultation.
Animals may recover from such pulmonary suppurations or if they are too extensive the consequent depletion may induce hectic and death.
Gangrene of the lung is happily rare and has appeared to be connected with close, foul stables, previous ill-health, and work after the onset of pneumonia. It is characterized by high temperature (106° to 108° F.) by great dulness and prostration due to the poisoning of the nerve centres, by weakness and unsteadiness, by complete loss of appetite, and at length an intolerable fœtor of the breath as if from putrefying animal matter. In rare cases recovery may take place, the dead portion having become detached and expectorated.
Consolidation from hepatization is the condition in which the inflamed lung is always found, in the second stage of the disease. The lung has then the density and brownish red appearance naturally belonging to the liver (red hepatization), which changes on the occurrence of softening of the exuded products to a grayish hue (gray hepatization). But after the subsidence of the acute symptoms, the process of liquefaction and absorption is not always complete, a portion of the exuded product becomes vascular, is developed into fibrous tissue and remains permanently impervious to air. Such is the state of the lung in many cases of thick or short wind in horses when these have occurred as a sequel of pneumonia. A horse suffering in this way has the breathing habitually accelerated and is thrown into a state of great distress by any attempt to make him perform hard work such as galloping, dragging a load up hill and the like. A chronic cough may equally accompany this condition.
Pathological Lesions. These differ according to the stage of the disease. In the first stage, that of congestion the lung tissue is engorged with blood as described under the head of congested lungs. As early as 6 or 7 hours after artificial irritation, the alveoli of the affected part are already filled by exudation and cell proliferation. Until this has taken place the alveoli can still be distended by blowing into the bronchial tube.
In the second stage the condition of the lung is that of red hepatisation, so called from its resemblance in color and consistency to the liver. There are gradations between congestion and red hepatisation. In the earlier stages of the latter, the lung retains a measure of its softness, elasticity and permeability to air, though it is considerably firmer and less permeable than that which is in a state of congestion and differs further from it in exuding from its cut surface not a grumous, dark bloody pulp, but a clear straw colored fluid. In the advanced red hepatisation the lung is of a firm consistency and granular liver like appearance. In color it varies from a bright red to a dark liver hue, the darker shades being chiefly met with in old animals or when the inflammation and fever have been intense and prostrating. Varying shades are seen in different lobules of the same lung. Its air cells are no longer pervious, it no longer crepitates under the pressure of the finger, nor floats in water, and its friability is such that it breaks down readily when the finger is thrust into its substance. Its surface is distinctly granular from the fibrinous plugging of the alveoli. Such a lung does not collapse when the chest is opened but retains its bulk and shape and in some cases the diseased portion may, by reason of the abundance of the exudation, be really larger than the same portion of lung in a normal state of dilatation. Its surface may thus retain the imprint of the ribs. Owing to the stasis of the blood in the vessels a hepatised portion of lung cannot be injected. The exudation which infiltrates the lung tissue and obliterates the air cells contains in the vicinity of the bloodvessels numerous granular masses and corpuscles and in the darker colored portions blood globules, owing to the action of diapedesis the red cells and the rupture of minute vessels. The smaller bronchial tubes stand out white and empty showing that they have escaped the inflammatory action. Hepatization usually extends from the anterior lobe or lower border upward.
Gray hepatization is a sequel of the red and presents the same firmness, friability and usually the same granular aspect; the lack of crepitation on pressure, and the higher density than water. From the cut surface a fatty or purulent fluid exudes spontaneously, or in other cases only when pressure is applied. The granular masses and corpuscles have disappeared, and if suppuration is not so abundant as to prove extensively destructive to lung tissue, that is gradually cleared up and restored to health. This state is always a very perilous one.
Abscess of the lung sometimes met with in animals dying of pneumonia shows a circumscribed area of inflammation and induration with the liquid pus in the centre immediately surrounded by a vascular (limiting) membrane. Abscess may be single or multiple though in the latter case it is commonly a symptom of pyæmia.
In gangrene of the lung the part may be in the dried condition of an eschar; it may indicate gangrene only by its altered color, its flaccidity, its fetid smell and the altered appearance of all its microscopic elements; it may be denoted by a putrid softening, the tissue easily breaking down into a stinking pulp of mixed fibrous and granular materials; or lastly there may be merely a cavity with traces of putrid contents, the dead mass having been detached, disintegrated and expectorated.
Modifications of the Blood and Distant Organs.
A marked feature of pneumonia is the destruction of red blood globules. This is early indicated in the staining of the visible mucosæ by the liberated hæmoglobin and by actual count they may be reduced in the horse from 7,500,000 to 6,000,000 per cubic millimeter (Trasbot). There is an increase of white globules, an absolute increase, not only in ratio to the red. The hæmatoblasts are enormously increased especially during defervescence. The fibrine (fibrine formers) is materially increased; in the horse from 3.5 to 6.7 or 7.5 per 1,000 (Grehaut). Albumen is diminished. Soda salts are increased. The bronchial lymphatic glands are always congested, swollen and reddened with some serous effusion. They may become the seat of inflammatory cell growth (embryonic tissue) or even of suppuration. The abscess may open into the bronchia or pleura. These are especially to be dreaded from their tendency to implicate the inferior laryngeal nerve and induce roaring.
Pleurisy is inevitable when the inflammation reaches the surface of the lung, hence hydrothorax is often present. Pericarditis and hydropericardium are similarly met with. Endocarditis is occasionally present and may be traced to strain of the valves of the laboring heart, or to direct infection with the pneumonia microbe. Dilatation of the right ventricle is common as a result of the obstructed pulmonary circulation.
Fatty degeneration of the heart and congestions of the intestinal mucosa, liver, kidneys, and spleen are further complications.
Finally laminitis and rheumatoid affections occur as complications.
Treatment. This must be adapted to the nature and condition of the subject and to the character of the disease. A horse in vigorous condition or with an acute type of inflammation may be greatly benefited by an actively depleting treatment, whereas to the same animal in a low state of health, or during the prevalence of an epidemic form of the malady depletion may be destruction. It is not sought here, as is so often done in the consideration of this disease, to ring the changes, as to the probability of a change of type in disease, or a change of theory on the part of physicians, having affected the practice of bloodletting. True to our primary purpose of rendering the work eminently practical, we shall first notice the general management applicable to all cases, then the treatment of the two great types of the disease, acute (sthenic), and subacute (asthenic), leaving to the enlightened judgment of the reader to apply an appropriately modified system to that large class of cases which occupy an intermediate position.
A pure airy box is first demanded, with the windows or doors toward the south, or at least not turned in the direction of the prevailing cold winds. The craving for pure air, so strikingly shown by the position which the animal assumes, ought never to be ignored nor neglected. We do not advocate the system of the late Professor Coleman who kept pneumonia patients in open sheds exposed to all vicissitudes of temperature winter or summer, and yet the fact that many recovered under such treatment as well as under a more rigorous system, having been turned out into the open fields amidst frost and snow, ought to open the eyes of all to the incomparable value of fresh air in this disease. The box then must be dry, cool and airy but without a cold exposure and without draughts of cold air.
Next in importance to pure, cool air is the comfort of the patient. Any tendency to chill, shivering, staring coat, or coldness of the surface and extremities is to be counteracted as far as possible. One or more blankets according to the condition of the patient and the temperature of the atmosphere are valuable and for the same reason a hood may be put on. Coldness of the limbs is to be met by active rubbing with the hand or with wisps of dry hay and then wrapping up loosely in flannel bandages. Some apply to the limbs ammonia and oil, spirits of turpentine, and other stimulants and thus by a powerful derivative action obtain an alleviation of the lung symptoms. For the same reason a mustard poultice on the chest, or the hot wet rugs recommended for congested lungs, often prove valuable in the earlier stages. Large injections of warm water and the supply of warm gruels are not to be neglected when they can be employed. Measures such as these directed to check any chill and render the circulation free and uniform in the skin and extremities, if adopted during the cold stages of the fever, will sometimes succeed in bringing about a resolution of the pulmonary congestion and warding off a threatened attack of pneumonia.
The diet should be of a non-stimulating and laxative kind. Bran mashes, linseed, oatmeal, or other gruels, carrots, turnips, scalded hay, or green food, if at the proper season, should be given in small quantities so as not to satiate.
Antiphlogistic Treatment. Half a century ago bloodletting was considered the remedy par excellence for pneumonia and it seemed justified by the marked relief to breathing and pulse which usually at once followed a free bleeding. In a short time, however, the fever would rise anew and the distressing symptoms reappear, which led the school of Broussais to repeat the bleeding, coup sur coup, as often as the exacerbation appeared. There was no respite for either age or condition, the debilitated city toiler, the babe at the breast, and man of eighty tottering into the grave had alike to submit to the lancet, and when the oppressive symptoms returned, the blood had to flow anew. Broussais himself, however, recognized his error in his later life, and remarkably enough, his conversion was effected through veterinary practice. His two carriage horses were successively attacked by pneumonia: the first was treated by bleeding coup sur coup and recovered: the second was put under a more conservative treatment and also got well, but while the first remained soft, flabby, debilitated and susceptible for a length of time, the second was on convalescence at once able to go into active work. The enormous abuse of bleeding, led to its more complete abandonment than would otherwise have been probable, and the contrast between the high mortality of cases treated by excessive bleeding, and the lower fatality in pneumonias treated without phlebotomy on the expectant (let alone) plan of Dietl or the stimulating method of Todd, Bennett and others, served to hasten its abandonment. Yet in bloodletting we have an instrument for good or evil which is not to be judged on slight evidence. The mere lessening of the blood pressure is to be little considered, as it requires the abstraction of nearly one-third of the entire mass of blood to visibly affect this. The vascular walls at once adapt themselves to the lessened amount. Nor is the mere lessening of the volume a vital point. After moderate bleeding this is made up in a few hours: after severe bleeding in 24 to 48 hours. The loss of adult red globules is more lasting. Bleeding to the extent of one per cent. of the body weight may have the number restored in seven days. The young red globules though rapidly produced have individually less hæmoglobin, and they can convey less oxygen to the tissues. This should mean less oxidation, less heat, less waste, less urea, uric acid, hippuric acid and other poisonous products in the tissues. Yet Baur says that in anæmia there is a greater metabolism of proteids and more excretion of urea. How easy it is to blunder in looking from one single point of view. Again after bleeding there is a great relative increase of the various forms of white blood globules, most of them young and therefore with somewhat altered functions. The paucity of red globules and excess of white are brought about by the pneumonia and independently of bleeding, so that it is difficult to say whether the phlebotomist is enhancing an evil, or helping a natural therapeusis. It seems hopeless to estimate the effects of these and other changes in the blood after bleeding, upon the metabolic processes of nutrition, secretion and sanguification. This digression has not been made to elucidate the results or the modus operandi of bleeding, but rather to illustrate the complexity of the problem involved and to warn against broad and unwarranted generalizations from insufficient premises.
Even today practitioners of the soundest judgment meet with a limited number of cases in which they resort to bleeding with advantage. These occur mainly in strong, robust constitutions, in individuals accustomed to an invigorating, open air life, liberal diet and abundant exercise. Even in these this measure is chiefly resorted to, to relieve an acute pulmonary congestion with a dangerous distension and over charging of a fatigued and overworked heart. In short the condition is one closely allied to acute congestion in which the value of bleeding is all but universally admitted. It is especially warranted early in the disease, though it may still be adopted with caution in a similar condition which has supervened at a later stage. A strong pulse and bright red mucous membranes, are not as has been supposed, essential prerequisites to its employment. The mucosæ may be pale, or more likely cyanotic, and the pulse small and weak, from the over charging of the heart and its tendency to failure, and it is to relieve these conditions that we adopt this most potent of all measures for securing a temporary lessening of the blood pressure in the right heart and pulmonary circulation. Even the transient relief may allow this to right itself and then less radical or dangerous measures may be relied on. Bleeding should very rarely be resorted to save at the outset of the disease; extensive exudation into the lung tissue strongly contra-indicates it; it cannot be safely employed in the very young or old, in weak or debilitated subjects, when the pneumonia has relapsed or supervened on another serious malady, or when occurring in an unhealthy district. Delafond met with a very high death-rate from bleeding in a damp undrained locality. Where bleeding is permissible, the blood should be drawn from the jugular in a full stream, from a large orifice, the finger being placed upon the pulse, and the flow arrested as soon as the blood is felt to pass along the vessel in a fuller, freer current, and the breathing is seen to be relieved. It can rarely be repeated with profit or safety, and in the vast majority of cases can be well dispensed with altogether.
Antipyretic Treatment. When the temperature runs dangerously high, a temporary use of antipyrin, acetanilid, phenacetin, or other potent antithermic remedy may be resorted to. But agents that so profoundly affect the heat centres are not devoid of danger and should not as a rule be continued after the dangerous excess of temperature has been overcome. They may be looked on as valuable to temporarily obviate an extreme danger rather than as a form of regular treatment.
The modern resort of applying ice bags to the chest may be similarly disposed of. In very high fever they have been apparently beneficial, but the danger of chill or injurious reaction is so great that they must be employed with the greatest possible consideration and care.
Refrigerant Febrifuge. Neutral salts such as saltpeter in 2 drachm doses every six hours may be given in the drinking water. These are valuable for their cooling and eliminating action, and possibly in counteracting the viscidity of the blood and exudations. Acetate of potash, bicarbonate of soda, iodide of potassium or muriate of ammonia may be substituted.
Stimulants. In debilitated subjects or with low fever or oppressed heart the stimulating diuretics like sweet spirits of nitre or liquor of the acetate of ammonia are to be preferred, and this is especially the case during convalescence. They at once sustain the flagging heart and aid in the excretion of morbid products. Digitalis is often of great value in the same sense, and as a heart stimulant nux vomica.
Some follow Todd and Bennett in seeking stimulation from alcohol, ammonia and its salts, ether, etc. When the circulation is weak or flagging these are often of value and they may even act directly on the pathogenic microbe. The inhalation of oxygen, or the solution of peroxide of hydrogen given by the mouth has often an excellent effect.
Sedatives. Aconite has become too much of a domestic remedy, nevertheless it may be used with advantage in high fever with excited heart action, to moderate the circulation and relieve the breathing. Veratrum, hydrobromic acid, bromide of sodium or ammonium, or chloral hydrate may be used as alternates or substitutes.
Compresses. Fomentations. Poultices. No measure is safer nor more promising, especially in the early stages, than the poultice jacket or compress. A blanket wrung out of hot water is wrapped around the chest, covered with a thick dry one, and held firmly attached by elastic circingles. Or soaked cotton wool is applied and covered with a dry blanket or a rubber sheet. The more acute the inflammation the more valuable is this measure.
Derivatives. As a derivative the mustard pulp rubbed in and covered with thick paper or rubber is especially valuable. In one hour it may secure a free exudation and material relief to the breathing. It may be replaced by ammonia and oil, with or without a covering, by hot water or by cantharides. This must however be used with judgment. In the early stage with a high type of inflammation and fever the surface irritation may aggravate this through sympathy; in such cases therefore the severity of the inflammation should first be moderated before using an active counterirritant. In debilitated conditions, too with an altered or depraved state of the blood and during the prevalence of a low type of the disease, sloughing may ensue from incautious blistering.
The repetition of the blister is often useful, the healing process going on simultaneously in the blistered surface and the diseased lung by virtue of nervous sympathy.
To complete recovery a course of vegetable tonics, such as gentian, nux vomica, calumba, may be given with iodide of potassium for a week or more. Constipation occurring during convalescence must always be corrected by food, (bran mashes, linseed gruel), injections, or oleaginous, saline, or aloetic laxatives. The greatest care should be exercised to secure pure air, comfort, sunshine, good grooming and general hygiene, and to prevent over-exertion during convalescence.
In the subacute types of pneumonia the fundamental difference in the treatment consists in the avoidance of all depressing remedies and the employment of stimulants and a supporting diet from the beginning. Sweet spirits of nitre and liquor of the acetate of ammonia, carbonate of ammonia or salammoniac with digitalis and strychnia may be used from the first. Vegetable tonics may be resorted to at an early stage, peroxide of hydrogen, and when expectoration is established and the fever moderated even mineral tonics may be employed. Nourishing gruels, mashes, roots, green food, and scalded oats may be used in turn to coax the appetite and not to satiate. In other respects the treatment is the same as for the acute. This form of the disease is liable to prove obstinate and persistent, and there appears to be a greater tendency to complications and so-called metastasis, as enteritis, laminitis or rheumatoid affections of the back or limbs. These when they occur must be treated as if they had arisen in ordinary circumstances, having regard meanwhile to the remaining inflammation in the lungs, for that has not necessarily been quite superseded but only alleviated.
Chronic Pneumonia. This has been described but if uncomplicated by consumption it appears to be usually only that consolidation of lung, due to the organization of exuded products into fibrous tissue, which occasionally forms a sequel of acute inflammation of the lungs. In such cases an access of circumscribed local congestion is liable to result from over-exertion, or a chronic state of irritation is maintained attended with more or less fever, inappetence, mal-assimilation, and often in the long run hectic, under which the animal is worn out. In such cases the chief indications are to avoid overwork or any undue strain upon the breathing organs, to support the patient by nourishing and easily digested food, and to control and remove any local irritation by measures indicated under the head of acute pneumonia.