Part 33

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.