Part 68

Complication of the lungs.—If at any time during the course of the fever the animal is exposed to cold or drafts of air, or in any other way to the causes of repercussion, the lungs may become affected. In the majority of cases, however, after three, four, or five days of the fever, congestion of the lungs commences without any exposure or apparent exciting cause. Unless this congestion of the lungs is soon relieved it is followed by an inflammation constituting pneumonia. This pneumonia, while it is in its essence the same, differs from an ordinary pneumonia at the commencement by an insidious course. The animal commences to breathe heavily, which is distinctly visible in the heaving of the flanks, the dilatation of the nostrils, and frequently in the swaying movement of the unsteady body. The respirations increase in number, what little appetite remained is lost, the temperature increases from 1 deg. to 2 deg., the pulse becomes more rapid, and at times, for a short period, more tense and full, but the previous poisoning of the specific disease has so weakened the tissues that it never becomes the characteristic full, tense pulse of a simple pneumonia.

On percussion of the chest dullness is found over the inflamed areas; on auscultation at the base of the neck over the trachea a tubular murmur is heard. The crepitant rales and tubular murmurs of pneumonia are heard on the sides of the chest if the pneumonia is peripheral, but in pneumonia complicating influenza the inflamed portions are frequently disseminated in islands of variable size and are sometimes deep-seated, in which case the characteristic auscultory symptoms are sometimes wanting. From this time on the symptoms of the animal are those of an ordinary grave pneumonia, rendered more severe by occurring in a debilitated animal. The cough is at first hacky and aborted; later, more full and moist. There is discharge from the nostrils, which may be mucopurulent, purulent, or hemorrhagic. As in simple pneumonia, in the outset this discharge may be "rusty," owing to capillary hemorrhages. We find that the blood is thoroughly mixed with the matter, staining it evenly, instead of being mixed with it in the form of clots. At the commencement of the complication the animal may be subject to chills, which may again occur in the course of the disease, in which case, if severe, an unfavorable termination by gangrene may be looked for. If gangrene occurs it is shown by preliminary chills, a rapid elevation of temperature, a tumultuous heart, a flaky discharge from the nostrils, and a fetid breath; the symptoms are identical with those which occur in gangrene complicating other diseases.

Complication of the brain.—At any time during the course of the disease congestion of the brain may occur; at an early period if the fever has been intense from the outset, but in ordinary cases more frequently after three or four days. The animal, which has been stupid and immobile, becomes suddenly restless, walks forward in the stall until it fastens its head in the corner. If in a box stall and it becomes displaced from its position, it follows the wall with the nose and eyes, rubbing it along until it reaches the corner and again fastens itself. It may become more violent and rear and plunge. If disturbed by the entrance of the attendant or any loud noise or bright light, it will stamp with its fore feet and strike with its hind feet, but is not definite in fixing the object which it is resisting, which is a diagnostic point between meningitis and rabies and which renders the animal with the former disease less dangerous to handle. If fastened by a rope to a stake or post, the animal will wander in a circle at the end of the rope. It wanders almost invariably in one direction. The pupils may be dilated or contracted, or we may find one condition in one eye and the opposite in the other.

The period of excitement is followed by one of profound coma, in which the animal is immobile, the head hanging and placed against the corner of the stall, the body limp, and the motion, if demanded of the animal, unsteady. Little or no attention is paid to the surrounding noises, the crack of a whip, or even a blow on the surface of the body. The respiration becomes slower, the pulsations are diminished, the coma lasts for variable time, to be followed by excesses of violence, after which the two alternate, but if severe the period of coma becomes longer and longer until the animal dies of spasms of the lungs or of heart failure. It may die from injuries which occur in the ungovernable attacks of violence.

Complication of the feet.—The feet are the organs which are next in frequency predisposed to congestion. This congestion takes place in the laminae (podophyllous structures) of the feet. The stupefied animal is roused from its condition by excessive pain in the feet and assumes the position of a foundered horse; that is, if the fore feet alone are affected, they are carried forward until they rest on the heels; and if the hind feet are affected, all the feet are carried forward, resting on their heels, the hind ones as near the center of gravity as possible. In some cases the stupor of the animal is so great that the pain is not felt, and little or no change of the position of the animal is noticeable. The foot is found hot to the touch, and after a given time the depressed convex sole of typical founder is recognized.

Pleurisy.—This is a rare complication, but when it does occur it is ushered in by the usual symptoms of depression, rapid pulse, small respiration, elevation of the temperature, subcutaneous edema of the legs and under surface of the belly, and we find a line of dullness on either side of the chest and an abscess of respiratory murmur at the lower part. If it is severe, there may be an effusion filling one-fourth to one-third of the thoracic cavity in from 36 to 48 hours.

Pericarditis is an occasional complication of influenza. It is ushered in by chills, elevation of the temperature; the pulse becomes rapid, thready, and imperceptible. The heart murmurs become indistinct or can not be heard. A venous pulse is seen on the line of the jugular veins along the neck. Respiration becomes more difficult and rapid. If the animal is moved the symptoms become more marked or it may drop suddenly dead from heart failure.

Peritonitis, or inflammation of the membranes lining the belly and covering the organs contained in it, sometimes takes place. The general symptoms are similar to those of a commencing pericarditis. The local symptoms are those of pain, especially to pressure on side of the flanks and belly, distention of the latter, and sometimes the formation of flatus, or gas, and constipation.

Other occasional complications are nephritis, hepatitis, inflammation of the flexor tendons and rupture of them, and abscesses.

Diagnosis.—The diagnosis of influenza is based upon continued fever, with great depression and symptoms of stupor and coma; the rapidly developing, dark-saffron, ocher, yellowish discoloration of the mucous membranes, swelling of the legs and soft tissues of the genitals. When these symptoms have become manifested the diagnosis of a local complication is based upon the same symptoms that are produced in the local diseases from other causes, but in influenza the local symptoms are frequently masked or even entirely hidden by the intense stupor of the animal, which renders it insensible to pain. The evidence of colic and congestion, which is followed by diarrhea, indicates enteritis. The rapid breathing or difficulty of respiration points to a complication of the lungs, but, as we have seen in the study of the symptoms, the local evidences of lung lesions are frequently hidden. Again, we have seen that inflammation of the feet, or founder, complicating influenza is frequently not shown on account of the insensibility to pain on the part of the animal, which indicates the importance of running the hand daily over the hoofs to detect any sudden elevation of temperature on their surface.

The diagnosis of brain trouble is based upon the excessive violence which occurs in the course of the disease, for during the intervening period or coma there is no means of determining that it is due to this complication. Severe cases of influenza may simulate anthrax in the horse. In both we have stupor, the intense coloration of the mucous membranes of the eyes, and a certain amount of swelling of the legs and under surface of the belly. The diagnosis here can be made only by microscopic examination of the blood. In strangles, equine variola, and scalma we have an intensely red, rosy coloration of the mucous membranes, full, tense pulse, and although in these diseases we may have depression, we do not have the stupor and coma except in severe cases which have lasted for several days. In influenza we have no evidence of the formation of pus on the mucous membranes as in the other diseases, except sometimes in the conjunctivae.

In severe pneumonia (lung fever) we may find profound coma, dark-yellowish coloration of the mucous membranes, and swelling of the under surface of the belly and legs; but in pneumonia we have the history of the difficulty of breathing and an acute fever of a sthenic type from the outset, and the other symptoms do not occur for several days, while in influenza we have the history of characteristic symptoms for several days before the rapid breathing and difficulty of respiration indicate the appearance of the complication. Without the history it is frequently difficult to diagnose a case of influenza of several days' standing, complicated by pneumonia, from a case of severe pneumonia of five or six days' standing, but from a prognostic point of view it is immaterial, as the treatment of both are identical. The fact that other horses in the same stable or neighborhood have influenza may aid in the diagnosis.

Prognosis.—Influenza is a serious disease chiefly on account of its numerous complications. Uncomplicated influenza is a comparatively simple malady, and is fatal in but 1 to 5 per cent of all cases. In some outbreaks, however, complications of one kind or another preponderate; in such instances the rate of mortality is much increased.

Alterations.—The chief alteration of influenza occurs in the digestive tract, and consists in hyperemia, infiltration, and swelling of the mucous membrane, and especially of the Peyer's patches near the ileocecal valve. The tissues throughout the body are found stained, and of a more or less yellowish hue. There is always found a congested condition of all the organs, muscles, and interstitial tissues of the body. The coverings of the brain and spinal cord partake in the congested and discolored condition of the rest of the tissues.

Other alterations are dependent entirely upon the complications. If the lungs have been affected, we find effusions identical in their intimate nature with those of simple pneumonia, but they differ somewhat in their general appearance in not being so circumscribed in their area of invasion. The alterations of meningitis and laminitis are identical with those of sporadic cases of founder and inflammation of the brain.

Treatment.—While the appetite remains the patient should have a moderate quantity of sound hay, good oats, and bran; or even a little fresh clover, if obtainable, can be given in small quantities. It is not so important that a special diet shall be observed as that the horse shall eat a moderate quantity of nourishing feed, and he may be tempted with any feed of good quality that he relishes. He should be placed in a well-ventilated box stall away from other horses. Grass, roots, apples, and milk may be offered and, if relished, allowed freely. To reduce the temperature the safest simple plan is to inject large quantities of cold water into the rectum. Antipyrene may be used with alcohol or strychnia. Derivatives in the form of essential oils and mustard poultices, baths of alcohol, turpentine, and hot water, after which the animal must be immediately dried and blanketed, serve to waken the animal from the stupor and relieve the congestion of the internal organs. This treatment is especially indicated when complication by congestion of the lungs, intestines, or of the brain is threatened. Quinin and salicylic acid in 1-dram doses will lower the temperature, but too continuous use of the former in some cases increases the depression. Iodid of potash reduces the excessive nutrition of the congested organs and thereby reduces the temperature; again, this drug in moderate quantities is a stimulant to the digestive tract and acts as a diuretic, causing the elimination of waste matter by the kidneys. Small doses of Glauber's salt and bicarbonate of soda, used from the outset, stimulate the digestive tract and prevent constipation and its evil results.

In cases of severe depression and weakness of the heart digitalis can be used with advantage. At the end of the fever, and when convalescence is established, alcohol in one-half pint doses and good ale in 1-pint doses may be given as stimulants. To these may be added 1-dram doses of turpentine.

In complications of the intestines camphor and asafetida are most frequently used to relieve the pain causing the colics; diarrhea is also relieved by the use of bicarbonate of soda, nitrate of potash, and drinks made from boiled rice or starch, to which may be added small doses of laudanum.

In complication of the lungs iodid of potash and digitalis are most frequently indicated, in addition to the remedies used for the disease itself.

Founder occurring as a complication of influenza is difficult to treat. It is, unfortunately, frequently not recognized until inflammatory changes have gone on for several days. If recognized at once, local bleeding and the use of hot or cold water, as the condition of the animal may permit, are most useful, but in the majority of cases the stupefied animal is unable to be moved satisfactorily or to have one foot lifted for local treatment; the only treatment consists in local bleeding above the coronary bands and the application of poultices.

During convalescence small doses of alkalines may be kept up for a short time, but the greatest care must be used, while furnishing the animal with plenty of nutritious, easily digestible feed, not to over-load the intestinal tract, causing constipation and consequent diarrhea. Special care must be taken for several weeks not to expose the animal to cold.

Prevention.—In order to prevent the introduction of the disease it is advisable to isolate newly purchased animals for at least a week. Further, the stabling of healthy horses in sales and feed stables should also be guarded against. At the beginning of an outbreak the disease may be checked by immediate isolation of the affected horses, by taking the temperatures of the healthy animals, and by the segregation of those showing a marked elevation.

Bacterial vaccines are now being prepared for the prevention of this disease and also for its cure, but to date the results are not convincing as to the beneficial action of these products. Since the cause of the disease has not yet been satisfactorily determined it is difficult to conceive how immunity could be produced with the aid of the germs which enter into the preparation of these products. The reports would indicate, however, that vaccines exert a favorable influence upon the course of the disease, probably preventing severe complications which under ordinary conditions are the principal factors in determining the severity of the outbreak.

CONTAGIOUS PNEUMONIA.

Synonyms.—Edematous pneumonia; stable pneumonia; equine pleuropneumonia; influenza pectoralis equorum; pleuropneumonia; influenzal pneumonia; Brustseuche (German).

Contagious pleuropneumonia is an acute contagious disease of horses manifesting itself either as a croupous pneumonia or a pleuropneumonia with complications in the form of serous infiltrations of the subcutaneous tissues and tendons.

Etiology.—Investigators of this disease incriminated various kinds of microorganisms as the cause of this affection. Transmission experiments were usually negative with these organisms. This was also the case in attempts to transmit the disease by feeding with affected parts of the lungs, intestinal contents, and nasal discharge; likewise by intravenous or subcutaneous injections of blood and of emulsions made from nasal discharge, urine, the lung, and other organs.

The most recent experimental results of Gaffky and Lueber proved that at least at the beginning of the disease the bronchial secretion contains the infection. Upon killing horses affected with the typical forms of the disease on the third or fourth day of the affection the air passages are usually found to be filled with a yellowish, tenacious, germ-free secretion with which they succeeded in infecting healthy colts. The virus has not been isolated. The possibility of its being a protozoan is suggested by the above-named investigators through their observations of round or rod-shaped bodies in the round cells of the secretions.

Two organisms were formerly especially considered to play an important part in the cause of the disease, the Streptococcus pyogenes equi, which has been isolated from most cases of the disease, and the Bacillus equisepticus, which by some investigators was considered to be the cause of contagious pleuropneumonia. Although there is no doubt as to the presence of these microorganisms in most of the cases, their association with the cause of this disease, however, is now doubted, especially since attempts to transmit the disease with pure cultures of these germs failed to reproduce the typical form of the disease. They, however, are of great significance in connection with the pathological changes occurring in connection with the infection and probably are the determining factor in the course of the disease. They exert their action after the animal has already been attacked by the true virus, and then produce the inflammatory changes attributed to these secondary invaders.

This disease is the adynamic pneumonia of the older veterinarians, who did not recognize any essential difference in its nature from an ordinary inflammation of the lungs, except in the profound sedation of the force of the animal affected with it, which is a prominent symptom from the outset of the disease. Again, this same prostration of the vital force of the animal, combined with the staggering movement and want of coordination of the muscles, caused it for a long time to be confounded with influenza, with which at certain periods it certainly has a strong analogy of symptoms, but from which, as from sporadic pneumonia, it can be separated very readily if the case can be followed throughout its whole course.

Infectious pneumonia is a specific inflammation of the lungs, accompanied with interstitial edema and inflammation of the tissues of these organs and a constitutional disturbance and fever. It causes a profound sedation of the nervous system, which may be so great as to cause death. It is sometimes attended with pleurisy, inflammation of the heart or septic complications, which also prove fatal.

Old, cold, damp, foul, unclean, and badly drained and ventilated stables allow rapid dissemination of the disease to other horses in the same stable and act as rich reservoirs for preserving the contagion, which may be retained for over a year.

The virus is but moderately volatile, and in a stable seems rather to follow the lines of the walls and irregular courses than the direct currents of air and the tracts of ventilation. Prof. Dieckerhoff found that the contagion of influenza was readily diffusible throughout an entire stable and through any opening to other buildings, but he also found that the contagion of infectious pneumonia is not transmissible at any great distance, nor is it very diffusible in the atmosphere. A brick wall 8 feet in height served, in one instance, to prevent the infection of other animals placed on the opposite side from a horse ill with the disease, while others placed on the same side and separated from the focus of contagion only by open bars in the stall were infected and developed the disease in its typical form.

Symptoms.—The symptoms differ slightly from those of a frank, fibrinous pneumonia, but not so much by the introduction of new symptoms as by the want of or absence of the distinct evidences of local lesions which are found in the latter disease. All the pneumonias throughout the whole course of the trouble are less marked and less clearly defined.

The symptoms may develop slowly or rapidly. If slowly, there is fever and the animal gives a rare cough which resembles that of a heavy horse affected with a slight chronic bronchitis; it becomes somewhat dejected and dull, at times somnolent, and has a diminished appetite. This condition lasts for several days, or the disease may begin with high fever, and the symptoms described below are severe and develop in rapid sequence. The respiration increases to 24, 30, or 36 to the minute, and a small, running, soft pulse attains a rhythm of 50, 70, or even more beats in the sixty seconds. The heart, however, contrary to the debilitated condition of the pulse, is found beating violently and tumultuously, as it does in anthrax and septic intoxication. The mucous membranes of the eyes and mouth and of the genital organs are found somewhat edematous, and they rapidly assume a dirty, saffron color, at times approaching an ocher, but distinguishable from the similar coloration in influenza by the want of the luster belonging to the latter and by the muddy, dull tint, which is characteristic throughout the disease.