Chapter X: Part 10

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.

CROUPOUS PNEUMONIA IN THE OX.

Subacute in many cases. Effect of temperament, and work. Acute form.
Symptoms. Decubitus. Unfavorable symptoms. Prognosis. Suppuration
frequent: indications. Gangrene. Colliquative Diarrhœa. Lesions,
Comparison with those of lung plague. Tubercle. Treatment, bleeding,
laxatives, refrigerant salts, derivatives, stimulants, tonics. Chronic
form. Symptoms. Treatment.

In the large ruminants this disease tends more towards a subacute type than in the horse, and coming on insidiously from ordinary causes is liable to be confounded with the _contagious pleuro-pneumonia_ of the bovine race. As in the horse the nervous animals show more violent symptoms. It is rare in milch cows and young cattle and more frequent in work oxen.

In the _acute form_ the symptoms mainly agree with those of the horse. There is the same shivering, followed by a hot stage, hyperthermia, the accelerated pulse, the short quick labored breathing, heaving flanks, cough frequent, deep, hacking, and easily excited, dilating nostrils, redness of the mucous membrane, and the same indications on auscultation and percussion, care being taken to obviate misconception of natural conditions in the chest of the ox. There is in addition a dry muzzle, tenderness of the back and breast bones and wincing when they are pinched between the fingers and thumb; suspension of the appetite and rumination and in cows suppression of the secretion of milk; the mouth is often opened and the tongue protruded to facilitate breathing, and in bad cases each expiration is accompanied by a moan or grunt. In many cases the ox can lie on his flattened breastbone and maintain the breathing process, but when the disease is severe he stands no less obstinately than the horse, his elbows turned out, his nose protruded and directed towards a window or other opening.

Among the unfavorable symptoms may be mentioned increasing anxiety and distress, a more oppressed breathing, the animal standing constantly in one position with legs apart, elbows turned out, his nose extremely raised, nostrils widely dilating, mouth open, tongue protruded, the expiratory grunt deep and prolonged, the cough infrequent and so weak as to be almost inaudible, being rather like a forced expiration, and the pulse rapid, feeble or imperceptible. The prognosis is favorable in moderate cases subjected to early treatment.

The termination by _suppuration_ is more frequent than in the horse. The general symptoms are ameliorated, appetite and rumination return though they remain capricious and irregular, there remains the double action of the flanks, the dry, rough muzzle, the tense, inelastic skin, frequently varying in temperature, the beast shivers at intervals, the cough is weak and often repeated, a yellowish thick discharge takes place from the nose, weakness and emaciation increases and the animal dies in from twenty to thirty days.

Gangrene of the lung sometimes supervenes and is indicated by similar symptoms as in the horse. In severe and prolonged cases a violent fetid diarrhœa often supervenes and hastens a fatal result.

The _post mortem_ lesions are similar to those of the horse. The cut surface of the hepatized lung, however, is divided into irregular red spaces by intersecting yellow lines—hence the name of _marbled lung_, from a supposed resemblance to that stone. The red spaces represent the pulmonary lobules and the whitish lines the surrounding areolar tissue which being especially abundant in ruminants and pigs stands out prominently when infiltrated with the yellowish exudation. There is then nothing specific in this appearance as has been erroneously supposed, it is merely the result of the different conformation of the lung in these animals and is always seen in the hepatized lung unless when from extravasation of blood into its substance the redness is rendered uniform. The amount of exudate into the interlobular tissue is, however, never so great as in lung plague.

The greater frequency of suppuration in the lung of the ox, as well as the greater tendency to tubercular deposit in prolonged cases are additional features in the diseased lungs.

_Treatment._ Blood-letting should be employed only with precautions, as in the horse. A saline laxative (1 lb. Epsom salts and ½ lb. molasses) may be used with advantage and safety early in the disease though in advanced stages it may sometimes prove dangerous from the tendency to diarrhœa. If constipation appears at a late stage injections of warm water and a mild laxative (6 ounces sulphate of soda) only, should be given. The purgative may be followed by the same neutral salts and in the same doses as for the horse. Counterirritants are of equal value. A mustard poultice may be kept on for several hours, or a mixture in equal parts of oil of turpentine, ammonia, and olive oil may be actively rubbed over both sides of the chest and repeated daily until tender. In Denmark a prompt and efficient blister is made with 1 part of Croton oil and 10 parts each of sulphuric ether and spirits of wine. This is rubbed actively over the chest and washed off as soon as a sufficient effect has been produced. It must be carefully watched to prevent blemishing.

In the low types of the disease and during convalescence stimulants and tonics are to be employed as recommended for the horse.

CHRONIC PNEUMONIA. Gellé describes a chronic form of this disease in cows. For about a month the patient became increasingly emaciated, there was a frequent, dry, weak cough, lifting of the flanks, and expiration double and accompanied by a moan. All these symptoms were aggravated by gentle exercise. Percussion detected dullness at the lower part of the lung and auscultation a distinct crepitating râle. The pulse was weak and rapid, the mucous membranes red and tumid, skin dry, ears and horns cold, appetite small and capricious, rumination rare, excrements soft, and milk almost dried up.

The _treatment_ is by diuretics with vegetable tonics and stimulants and active counterirritation over the chest. Gellé considers the malady as all but incurable unless active blistering is promptly employed so soon as the malady has assumed the chronic form and before extensive structural changes have taken place in the lungs.

CROUPOUS PNEUMONIA IN SHEEP.

Causes, damp, cold soils, inclement weather, cold rains, hard driving,
shearing or washing in cold weather, change to a cold climate, or from
a warm barn, hot barns, heavy fleeces, sudden plethora. Symptoms, in
congestive cases, in inflammatory. Treatment, preventive, hygienic,
antiphlogistic, laxative, febrifuge, derivative.

This disease is not infrequent in these animals, occurring enzootically in low, wet pastures; or from cold storms of wind, sleet or drenching rains, particularly after hard driving, or shearing; or from washing during inclement weather. Dressing with mercurial ointment in cases of _scab_ is a frequent cause of pneumonia and death in Lincolnshire and various other English counties. Lastly M. Seron in Hurtrel d’Arboval’s “_Dictionaire_” describes its prevalence in _Seine-Inférieure_ among low conditioned sheep subjected abruptly to a very nutritious diet. The hot buildings, heavy fleeces, and sudden plethora, appear to conduce to dangerous pulmonary congestions. The _symptoms_ do not differ materially from those seen in the ox except so far as they are modified by the fact that the disease often terminates fatally before hepatization has been established and the symptoms and post mortem appearances are those of congestion and sanguineous engorgement of the lung rather than of hepatization.

This engorged state of the lungs it is which has led Youatt and others to describe them erroneously as “gangrenous” and shepherds to name the disease “rot of the lights.” The condition is that of acute congestion and analogous to that seen in congested lungs in the horse.

The _treatment_ ought to be chiefly preventive and will consist in the avoidance of the causes above indicated.

When the disease has set in, fresh air, and general comfort, bleeding if in the very earliest stages and in a strong patient, purging (3 ounces sulphate of soda and ¼ lb. treacle in warm gruel) and a free supply of nitre (about ½ an ounce daily to each) in the water or gruel supplied are the leading indications. As a counterirritant aqua ammonia acts well being sufficiently confined by the fleece.

PIG. PNEUMONIA.

Symptoms, chill, burrowing, hot skin, cough, disturbed breathing,
indications of exudation. Treatment, laxative, sedative, nauseant,
febrifuge, wet jacket, blister.

Hogs are not exempt from this disease. They show the same symptoms of chill with hiding under the litter, followed by a hot stage, cough, hurried breathing, and (if the clothing of fat is not too thick) conclusive results on auscultation and percussion.

As _treatment_ bleeding from the ears and tail is sometimes resorted to with questionable benefit. A laxative of three ounces of castor oil or three or four croton beans given in the food is of value. Tartar emetic in doses of ¼ grain and nitrate of potash in 10 grain doses should be shaken on the tongue at least four times daily to keep up a continued nausea and action on the urinary organs. The tartar emetic so worthless in the larger animals is of value in the pig and dog. A damp compress or blister may be used. The skin of the animal is difficult to blister, but by the use of the Danish croton liniment, mentioned for the ox, of hot water, or of a mixture of oil of turpentine and croton, 8 parts of the former and 1 part of the latter, a sufficient effect can usually be obtained.

DOG. PNEUMONIA.

Breeds most liable. Causes, over-exertion, cold baths, clipping,
exposure in cold, distemper. Symptoms, chill, fever, disturbed
breathing, cold extremities, cough. Treatment, dietary, nursing,
laxative, nauseant, febrifuge, moist jacket, mustard, stimulants,
tonics, heart tonics and careful nutrition during convalescence.

This is a frequent affection in hounds. In hunting or coursing dogs the causes are like those operating in the horse. The clipping of long haired dogs in inclement weather, swimming dogs in winter without afterwards drying or heating them by exercise, and shutting them out of doors at night, when accustomed to a warm dwelling are occasional causes. It sometimes occurs epizootically and frequently supervenes during distemper.

The chief _symptoms_ of chill, fever, and difficulty in breathing are like as in other animals, while the results of auscultation and percussion are more satisfactory than in any other domestic animal. The dog sits on its haunches to facilitate breathing; his elbows turned out, his mouth open and his tongue protruded. Coldness of the ears and a short quick cough are usually marked symptoms.

_Treatment._ The general care applicable to other animals is equally demanded here. The diet should consist of mild broths, or farinaceous foods with a little gravy if necessary to render it palatable.

Bleeding from the jugular has been recommended and may be admissible at the outset of the disease in a very few appropriate cases. If costiveness exists a tablespoonful of castor oil may be given (more or less according to the size of the animal), following this up by the tartar emetic, nitre and sugar recommended for bronchitis. The poultice jacket is of great value. Mustard poultices may later be applied to the sides of the chest. Stimulants, tonics and nourishing diet may be required during convalescence, or when the disease assumes a low type.

CROUPOUS PNEUMONIA IN FOWLS.

In chickens exposure and neglect are alleged causes. Foul coops and the contrast between the warm building and cold outer air are justly blamed. Ruffled feathers, drooping head, dark colored comb and wattles, trailing wings, a disposition to gape, panting and cough are noticed. Under the wings and over the back crepitations and dulness may be detected. The patient may take a teaspoonful of castor oil, and saltpetre or iodide of potassium may be given in the drinking water. In careful doses the other remedial measures may be attempted.

_Pneumonia in birds._ Causes, exposure, neglect, foul coops, hot, close houses, etc. Symptoms, erect plumage, drooping head, wings, and tail, dark comb, gaping, panting, cough, crepitation. Treatment, hygienic, laxative, febrifuge.

ACUTE PLEURISY IN THE HORSE. PLEURITIS.

Causes, cold, damp, soils and exposures, as with rheumatism, youth,
vigor, heavy diet, digestion, or hepatic disorder, over-exertion,
perspiration and succeeding chill, wading or swimming rivers, standing
in snow, salted snow, rain, sleet, snow, draughts between open doors
and windows, clipping, cold sponging of legs, tuberculosis, a common
cause in man and cattle is rare in horses, surface pneumonias,
cancers, actinomycosis, tumors. Traumas from broken rib, penetrating
intercostal wound, blows, contusions, ruptured pulmonary or
intercostal abscess. Irritant (infectious) exudate suggests microbes.
Symptoms, chill, reaction, partial sweats, pawing, pointing one foot,
hyperthermia, hard, jarring pulse, hurried breathing, inspiration
catching, pleuritic ridge, uneasy movements, hacking cough, tumors and
twitching of chest muscles, tender intercostals, grunting, friction
sound, subsiding with appearance of dull area below, signs of
effusion, relief, dyspnœa, lifting flanks and loins, perspirations,
stocking limbs, pasty swelling on sternum, effusion of same level on
both sides, creaking sounds, splashing, gurgling, metallic tinkling,
weakness, sinking. Signs of adhesions, compression of lung, abscess.
Duration. Lesions, early formation of false membranes, pleuritic
effusion, its composition, its color at different stages, dry
pleurisy, sero-fibrinous, sero-fibro-purulent, hydro-pneumothorax,
tubercle. Prognosis. Treatment, during the chill, warm air, clothing,
drinks, injections, compresses, pilocarpin during early inflammatory
stage, derivatives, dry cupping, mustard, cantharides, hot water, or
air, cold applications, laxatives, calmatives, antirheumatics,
alkaline agents, with bitters, diuretics, heart tonic, iodine,
mercury, thoracentesis.

_Causes._ Pleurisy is common in all domestic animals and especially so in cold, damp, exposed localities which suffer equally from rheumatism. It occasionally extends to the fascia of the limbs, the joints, or the navicular or other trochlea as a rheumatic affection. The disease is prevalent among young and vigorous horses, four or five years old, on stimulating feeding. Here hepatic derangements and poisons, over-exertion, perspiration and succeeding chills are especially to be suspected. Plunging the limbs in ice cold water as in wading a river (Fromage), standing in snow and above all in salted snow, or facing a cold rain, sleet, or snow when perspiring or fatigued, are recognized causes. A full drink of ice cold water when freely perspiring, and followed by standing in the frosty air, or in a cold current indoors. Exposure unblanketed after clipping in winter (Field, Trasbot), and even sponging the body or legs with cold water when heated or fatigued or both. St. Cyr found that pneumonias stood to pleurisies as 3: 1, Trasbot as 10: 1, yet the latter draws attention to the fact that in cavalry horses habituated to the stable and sent out into camps in the depth of winter, the pleurisies are more numerous than pneumonias. This may suffice to show the importance of the rôle filled by cold and chill in the production of pleurisy. Yet many physicians look upon the chill as a predisposition only, while the true origin of disease is microbian. And in man a large proportion of pleurisies appear to be distinctly tuberculous. Bowditch traced 90 cases of acute pleurisy and found that 32 had tuberculosis. The objection to generalizing too largely on this for the lower animals is that the horse and dog, in which tuberculosis is rare, are by far the most common subjects of pleurisy, whilst cows which are very prone to tuberculosis show few cases of simple pleurisy. Again we find pleurisy in the horse as the result of other diseases localized in or adjacent to the pleura, and where there is nothing to indicate tuberculosis. Thus it follows pneumonia approaching the surface of the lung, cancers, actinomycosis and other tumors, and traumas—a pulmonary abscess bursting into the pleura, a broken rib scratching and lacerating the lung, a perforating wound of the intercostal space, or in cattle a sharp pointed body advancing from the reticulum toward the heart.

But the presumptive absence of the tubercle bacillus in the great majority of pleurisies in the horse does not prove the absence of all pathogenic microbes. Trasbot, who rejects the microbian theory, found that the injection of a little of the exudate into the pleural cavity of a sound horse, always determined a generalized pleurisy. Injections of distilled water with the same antiseptic precautions, made separately by himself and Laborde, had no pathogenic effect. Trasbot attributes the pleurisy vaguely, to the irritant effect of the exudate, but if it should finally be shown that this exudate contains microbes, though they may not be those of tuberculosis, the irritant action will be much more clearly explained. There are forms of pleurisy which are unquestionably the result of microbes, as in lung plague, influenza, canine distemper, glanders, tuberculosis, pneumo-enteritis, actinomycosis, and theoretically it might be supposed that in our ordinary acute pleurisies, other germs that have been lurking harmless in the system may take occasion by reason of the lowered vitality induced by a chill, or a trauma, to colonize the thoracic serosa and develop pleurisy. Under such a theory, the predisposing and microbian element would remain equally effectual, but only operative when conjoined, neither being pathogenic without the other.

Until the constancy of the microbian factor is demonstrated we must recognize the time honored doctrine, that pleurisy may be due to cold, exposure, over exertions, to traumatic injuries, blows, concussions, fractures, penetrating wounds, and to extension by contiguity from adjacent diseases.

Most commonly pleurisy is unilateral on the right side but is often on the left or on both sides.

_Symptoms._ There is the early symptom of shivering followed by a hot stage in which the limbs participate and partial sweats bedew the surface. There are first uneasy movements of the fore limbs with some lifting of the flanks and this discomfort increases until the patient is panting with pain and occasionally glancing round at his heaving flanks and even pawing as in colic. If the pleurisy is confined to one side the corresponding fore limb is often advanced before the other. The temperature is 102° and upward. The pulse is quick, hard and incompressible being usually compared to a jarred wire and beats from 48 to over 60 per minute. The breathing is highly characteristic. It is hurried, is carried on chiefly by the abdominal muscles to avoid the rubbing of the inflamed pleuræ on each other, and has the inspiration short and suddenly checked by an audible closure of the glottis while the expiration is slow and prolonged. This character of the breathing is well observed when the ear is placed against the false nostril. The laboring abdominal muscles stand out as a ridge from the outer angle of the ilium along the lower ends of the last ribs (pleuritic ridge). A tremor on this line is often noticeable in the early stages. It may also be felt by the hand laid on the costal region. The horse does not stand obstinately still as in pneumonia, but frequently moves as if seeking an easier posture. The short, hacking cough contrasts with the deep, rare cough of pneumonia. The expired air is not so hot, nor the mucous membrane of the nose so red as in the last named disease and there is no nasal discharge. A twitching of the muscles of the chest is sometimes seen and if the intercostal muscles are pressed upon, the animal winces and frequently grunts. This last symptom is likewise seen in rheumatic disease of the intercostal muscles (pleurodynia) but the absence of the fever, the cough, and other chest symptoms sufficiently distinguish this. Auscultation detects in the early stages in addition to a healthy respiratory murmur, a friction sound audible in inspiration only in short jerks near the close of the act and comparable to the rubbing of the palm of one hand over the other laid over the ear, but this is no longer heard when effusion of liquid has taken place into the pleuræ. Percussion in the early stages detects no change from the healthy chest resonance.

If not relieved in from twenty-four to thirty-six hours, a remarkable modification of the symptoms takes place indicating the occurrence of effusion. The violent symptoms are suddenly relieved. The quick catching breathing which is in many cases accompanied by a grunt, becomes easy and though fuller than natural is comparatively regular. In particular the inspiration is free and full and comparatively painless, the sudden check and the grunt by which it was arrested having alike disappeared. The tension of the abdominal muscles and the tucked up appearance of the flanks give way; the pulse acquires a softer character, the haggard pinched countenance is relaxed, and a general appearance of comfort and even liveliness prevades the animal. This temporary improvement is often so great that the horse will take to feeding as if he had all at once recovered.

The apparent recovery is, however, only transient. Soon the pulse becomes more frequent and loses its fulness, the breathing is more laborious and attended with a characteristic lifting of the flanks and loins, the nostrils are widely dilated, the limbs outstretched and the elbows outturned, the eyes stare and project and the countenance has a haggard appearance indicating threatened suffocation. Partial sweats may break out on the surface, due to the state of nervous excitement and general relaxation and supplementing in some degree the impaired exhalation from the lungs. Auscultation over the lower region of the chest shows a complete absence of the respiratory murmur, rising to the same level precisely at all points. Percussion elicits no resonance on the same region. If the effusion has taken place slowly or existed for some time, the dulness and absence of sound will usually indicate that the liquid rises to the same level on both sides. So thin and permeable is the posterior mediastinum in its lower part that unless thickly coated by new solid exudations, the effusion readily passes through it and rises to the same height on both sides. If gas as well as liquid is produced in the pleural sac a gurgling or splashing sound may be heard on auscultation, and occasionally, after rising or other change of position, a _metallic tinkling_, due to droppings from the shreds of false membranes above into the fluid below.

As the disease proceeds dropsical effusions are observed beneath the skin of the breast and abdomen, a mucous rattle is heard in the trachea, the nose, ears and limbs become cold, the pulse increases in rapidity and weakness, shows the distinct anæmic tremor or thrill, and becomes rapidly imperceptible; the horse moves unsteadily and often falls suddenly dead.

This early fatality is, however, only seen in the worst cases. In those about to terminate favorably improvement is shown usually about the fourth day. The lifting of the flanks and loins becomes moderated, the ribs move more freely, the grunt ceases, the pulse is fuller, softer and less frequent, and auscultation and percussion show a steady decrease in the effusion. Appetite meanwhile returns, the horse moves more freely, lies down for a length of time in succession, and convalescence lasts from two to three weeks.

In the less fortunate cases structural changes more or less permanent, keep up symptoms of illness for a variable length of time. Sometimes after the liquid effusion has been absorbed the lung remains attached to the side of the chest by newly formed tissue (false membrane) and while this is undergoing a drying and organizing process, it gives rise to a leathery, creaking sound heard on auscultation and easily mistaken for crepitation. Sometimes an abscess forms on the surface of the pleura or in the newly organized false membrane, and either bursts into the pleural sac (empyema) where it serves to increase and sustain the irritation, or it makes its way through the intercostal spaces and is discharged externally. In this last case its advance toward the surface is heralded by an extensive inflammatory infiltration and pasty swelling much more tender to the touch than the dropsical swelling already referred to. Another condition is that in which false membranes of considerable thickness invest a lung and, following the law of all fibrous structures in process of organization, they contract and cause a compression and partial collapse of the contained lung tissue. A flattening of the corresponding side of the chest and a muffled and almost inaudible respiratory murmur is the result of this condition. In some measure these symptoms are present during convalescence in all cases of pleurisy since the lung never expands to its full size till some time after apparent recovery, but it is only when the organ is invested with false membrane that the symptoms are very apparent.

In all such cases of prolonged pleurisy from protracted structural change there is continued illness without the violent symptoms by which the acute form of the disease is manifested. The acute suffering, the restlessness, the grunt, and even the catching breathing may be absent; the temperature may be almost reduced to the healthy standard, the pulse small and tolerably soft, the appetite considerably improved and the different secretions tolerably normal; yet the pinching of the intercostal spaces causes sharp pain, and measurement, auscultation and percussion testify to the persistence of disease. The animal is hidebound, unthrifty and unequal to any exertion. The cough is weak and painful and sometimes accompanied by a grunt.

Besides the changes connected with exudation and effusion, and organization or suppuration in the exuded products, _gangrene_ sometimes results. A case of this kind is related by _Percivall_.

The _duration_ of pleurisy may thus extend from two days in very acute cases to several weeks, or even months if we estimate it by the continuance of _hydrothorax_ in the chronic cases.

_Post Mortem Appearances._ These consist mainly in the presence of false membranes lining the pleura and hanging in cobweblike shreds into the cavity of the chest, and of the liquid effusion which fills up the chest at its most dependent part. The pericardium also contains fluid in many cases. The periods at which exudation takes place, and when the principal changes take place in the exuded materials have been well investigated by Dupuy, Hamont, Delafond and St. Cyr. They induced pleurisy by injecting irritant liquids into the chest, and noted the regular sequence of changes.

Dupuy injected two drachms of oxalic acid dissolved in three ounces of water. Symptoms of pleurisy at once came on, with the friction sound characteristic of its early stages. Next day friction sound had ceased and evidence of effusion existed. The same experiment repeated on several horses showed that if killed at any period subsequently to this, considerable exudation had already taken place. In one horse in which the disease was of 50 hours’ standing the chest contained 43 pints of citrine-colored fluid, and abundance of yellow, thick, false membrane enveloping the costal and pulmonary pleuræ.

Hamont injected seven ounces of a weak solution of tartaric acid into the left pleural sac, repeated the injection next morning and destroyed the horse twenty minutes afterward. The chest opened immediately showed a small amount of liquid on the affected side, and the pleura injected and reddened.

Delafond made twenty-two experiments with the same general result.

Percivall found recent adhesions between the lungs and side so early as seventeen hours after the commencement of the pleurisy.

Andral injected rabbits with acetic acid and in nineteen hours found in the injected pleura soft, thin, false membranes traversed by red anastomosing lines, and in certain cases a serous or puriform fluid.

W. Williams found a false membrane formed twenty-four hours after the injection of the irritant.

St. Cyr in a series of 43 experimental and casual pleurisies in horses, found that in a very few hours there was marked local congestion and swelling of the pleura speedily followed by the formation of soft, pulpy, friable false membranes, largely amorphous and granular but impregnated with many cells and nuclei. These adhere feebly to the pleura but may accumulate with prodigious rapidity so as to cover in three or four days the whole pleural surface on one or both sides. The attendant serous effusion was bloody, turbid, or lactescent. The pleural surface under the false membrane was highly vascular and studded with fragile, red conical elevations projecting into the membrane. Exceptionally the sub-serous connective tissue became the seat of exudation as well.

From the sixth to the ninth day the false membranes began to become vascular and from the tenth to the fourteenth day commenced to organize into the connective tissue. With the advent of this stage, the inflammatory action tended to subside, and the reabsorption and repair to ensue.

_Pleuritic effusion._ This varies greatly at the different stages of the disease. As effused it has a composition resembling that of the blood:—

Water, 911 to 924
Albumen, 63.33 to 82.50
Fibrine formers, 2.16 to 12.50
Extractive matter.
Salts.

The progressive changes from the hæmorrhagic effusion to the limpid hydrothorax and their relation to the different stages of the disease and the subsidence of the inflammation are of the greatest importance in deciding questions of responsibility, when the animal has recently changed hands. St. Cyr has classified his cases in the following instructive table:

─────────────────────┬─────────────────────────────────────────┬───────
Duration of the │ │
Disease. │ Effusions. │Total.
─────────────────────┼──────┬─────────────────┬────────┬───────┼───────
│ Port │ │Muddy or│ │
│Wine. │Sero-sanguineous.│Grayish.│Limpid.│
─────────────────────┼──────┼─────────────────┼────────┼───────┼───────
From 1st to 7th day.│ 9│ 6│ 3│ │ 18
„ 8th to 15th day. │ 2│ 3│ 4│ 6│ 15
„ 16th to 30th day. │ │ 1│ 1│ 5│ 7
After 30th day. │ │ │ │ 3│ 3
─────────────────────┼──────┼─────────────────┼────────┼───────┼───────
│ 11│ 10│ 8│ 14│ 43
─────────────────────┴──────┴─────────────────┴────────┴───────┴───────