_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, hepat.i.tis, 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 interst.i.tial 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 circ.u.mscribed 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 appet.i.te remains the patient should have a moderate quant.i.ty of sound hay, good oats, and bran; or even a little fresh clover, if obtainable, can be given in small quant.i.ties. It is not so important that a special diet shall be observed as that the horse shall eat a moderate quant.i.ty 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. Gra.s.s, roots, apples, and milk may be offered and, if relished, allowed freely. To reduce the temperature the safest simple plan is to inject large quant.i.ties of cold water into the r.e.c.t.u.m. 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 quant.i.ties 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 princ.i.p.al 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 Luber 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 pa.s.sages 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 a.s.sociation 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 a.n.a.logy 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 interst.i.tial edema and inflammation of the tissues of these organs and a const.i.tutional 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 appet.i.te. 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 a.s.sume a dirty, saffron color, at times approaching an ocher, but distinguishable from the similar coloration in influenza by the want of the l.u.s.ter belonging to the latter and by the muddy, dull tint, which is characteristic throughout the disease.

Suddenly, without the preliminary rales which precede grave lesions of the lungs in other diseases, the blowing murmur of pneumonia is heard over a variable area of the chest, usually, however, much more distinctly over the trachea at the base of the neck and directly behind the shoulder on each side of the chest. In some cases the evidence of lung lesion can be detected only over the trachea. The lesions of the lungs may be scattered throughout both lungs, involving numerous small areas, or they may be confined to and more or less fully occupy one or two lobes. Occasionally there is a general involvement of both lungs.

The body temperature has now reached 104 or 105 F., or in extreme cases even a degree higher. The debility of the animal is great without the stupefaction or evidence of cerebral trouble, which is constant with such grave const.i.tutional phenomena in influenza or severe pneumonia.

The animal is subject to occasional chills, and staggers in its gait.

The yellow coloration of the visible mucous membrane is rendered pale by infiltration of the liquid of the blood into the tissues; the pulse may become so soft as to be almost imperceptible, the heart movement and sounds being at the same time exaggerated. The animal loses flesh rapidly, and dropsies of the extremities, of the under surface of the belly, or of the internal organs may show themselves.

_Terminations._--These symptoms may gradually subside after five to eight days, with an improved appet.i.te the inanition may cease and the animal commence to nourish its impoverished blood and tissues; the pulse becomes stronger and the heart more regular and less tumultuous; the mucous membranes a.s.sume a brighter and more distinct color; the difficulty of respiration is removed, and the animal may make a recovery. When death occurs it is usually directly due to heart failure; in some cases it is caused by asphyxia, owing to the great amount of exudation into the lung tissue, rendering its further function impossible.

_Complications._--The pulmonary complications of infectious pneumonia are secondary inflammatory or necrotic changes in the lungs themselves.

Suppuration at times takes place in the bronchi and may extend to the lung tissue. In this case mucous rales develop which are most distinctly heard over the trachea and on the sides of the chest directly behind the shoulders. With the development of the mucous rales, to be heard on auscultation, we have a more purulent discharge from the nostrils, similar to that of a chronic or subacute bronchitis. If the inflammation has been of some standing, cavernous rales may be heard, indicating the destruction of a considerable portion of lung tissue and the formation of a cavity. The effects of this more acute inflammatory process are not appreciable in the general condition of the animal, except to weaken it still further and add to its debilitated and emaciated cachexia.

Gangrene sometimes occurs. A sudden rise of the body temperature of 1 or 2, with a more enfeebled pulse and a still more tumultous heart, develop simultaneously with the appearance of a discharge from the nostrils. This discharge is gray in color, serous or watery in consistency, mixed with the detritus of broken-down lung tissue, and sometimes contains clots of blood, or in more serious cases may be marked by a quant.i.ty of fluid blood from a hemorrhage, which proves fatal. The discharge is fetid to the smell. The animal emaciates rapidly. On examination of the lungs mucous rales are heard in the larger bronchi, cavities may be found at any part of these organs, and points of lobular pneumonia may be detected.

A very serious complication is an inflammation of the heart muscle. This is shown by a very weak and rapid pulse, great prostration, some filling of the lungs. This complication nearly always terminates in death. Other complications which may be mentioned are inflammation of the kidneys, blood poisoning, congestion of the brain, and inflammation of the tendinous sheaths and the tendons of the legs.

_Diagnosis._--As fever is the first symptom of infectious pneumonia, it is useful during an outbreak of this disease to make daily temperature measurements of the exposed horses, so that the first indication of disease may be discovered and the horse removed from contact with those that are sound.

_Prognosis._--The mortality in this disease may be as high as 25 per cent, but it is usually not more than 10 per cent. If there is a special tendency to complications of some sort, the mortality is increased.

_Alterations._--At the time of death from infectious pneumonia we frequently find septic changes and the evidences of putrefaction. The solidification of the lung tissue is found irregular in shape and high around the root of the lungs and the large bronchi, and is generally covered by sound lung tissue. The anterior lobes of the lungs are usually entirely affected. The diseased portion appears of a gray-yellowish color, somewhat watery, and tears readily. Matter is found in the air tubes which form gutters through the jellylike ma.s.s of the diseased lung. Abscesses from the size of a nut to larger ma.s.ses may be found throughout the lungs. The blood is dark in color, fluid, or only clotted into soft, jellylike ma.s.ses. Ma.s.ses of gangrenous or dead-black tissue may be present.

_Treatment._--Bleeding is not to be used, because it would only still further weaken an already enfeebled animal; antimony or the alterants would increase the depression of a too-depraved const.i.tution. There is in this disease no acute congestion of a particular organ to draw off by depletive measures, nor any violent blood current to be r.e.t.a.r.ded, for fear of hypernutrition of any special part.

Revulsives do good, as they excite the nervous system and awaken the torpor of the weakened blood vessels, which aid in the reestablishment of the functions. As in other diseases, mustard poultices may be applied over the belly and sides of the chest, but caution must be used in the employment of blisters, as ugly ulcers may result from their action on a tissue of weakened vitality. Setons are dangerous from the great tendency in this disease to septic complications. Repeated friction of the legs by hand-rubbing and warmth by bandaging and by rubbing the surface of the body with turpentine and alcohol, which is immediately to be dried by rough towels, will excite the circulation and stimulate the emunctories of the skin.

Stimulants are given internally from the outset of the disease.

Turpentine in 1-dram doses regulates the heart and excites the kidneys to carry off waste matter, but if repeated too frequently may disturb the already delicate digestive system. Alcohol rectifies the latter danger, and is a useful stimulant to the heart and digestive system, if given with care in small doses. It is an antiputrid, and is especially indicated when septic complications and gangrene are present. The aromatics and bitter tonics are useful; gentian and tea in warm decoction form a useful menstruum for other remedies. Digitalis is a useful remedy. Strychnin and quinin may be given throughout almost the whole course of the disease. The various preparations of iron are astringents and excitants to the digestive system. Carbolic acid is an antiputrid which is of marked benefit in edematous pneumonia; it should be given in small doses diluted in alcohol.

Salicylic acid may be given in 1 or 2 dram doses every few hours. It is much used for troubles of the serous membranes, lowers the temperature, and is of value in this disease in preventing the exudation into the tissue of the lungs. The alkalines, as the sulphate and bicarbonate of soda, the nitrate of potash, and very small doses of the iodid of potash, should be employed to regulate the digestive tract, the kidneys, and the other excreting glands, and to stimulate absorption of the waste matter.

The biological products enumerated under the treatment of the catarrhal form of influenza are also recommended for this disease. The bacterial vaccines in particular are being employed to a great extent, but the results are not uniformly satisfactory, especially with regard to prevention. They might, however, exert a beneficial influence against an attack of the secondary invaders and complications. A serum is also being prepared especially for the treatment of this disease, and since this is obtained from animals which have been highly immunized against the various organisms found in a.s.sociation with influenza it no doubt is beneficial, especially when the life of the animal is threatened. Such serum, however, should be used in sufficiently large doses, as repeated experience has proved that small doses have no beneficial action on the disease.

More recently salvarsan is being highly recommended for the treatment of the pneumonic form of influenza, and by many investigators it is considered as a specific for this affection. A single injection of this preparation is supposed to result in a rapid clearing of the lungs and the recovery of the animal is hastened. The cost of this product, however, at the present time, is exorbitant, and it should be considered only in the treatment of very valuable animals.

The same procedure as given for influenza should be carried out in the prevention of this affection.

The diet demands the strictest attention from the outset. In many of the fevers the feed has to be diminished in quant.i.ty and regulated in the quality of its heat-producing components during the acute part of the disease, so as to lessen the material for combustion in the inflamed organs. In edematous pneumonia, on the contrary, all the feed that can possibly be digested and a.s.similated must be given. Choice must be made of the richest material which can be handled by the weakened stomach and intestines without fatiguing them. Good, sound hay should be chopped short and dampened or partly boiled; in the latter case the hay tea can be reserved to use as a drink. Oats may be preferred dry or in other cases are taken better scalded; in most cases, however, it is better to give slops of oatmeal, to which may be added a little bran, barley flour, or boiled milk and wheat flour. Pure cow's milk, not too rich in fatty matter, may be given alone or with beaten eggs; frequently the horse has to be coaxed with the milk diluted with several parts of water at first, but will soon learn to drink the pure milk. Apples and carrots cut up raw or boiled are useful, and fresh clover in small quant.i.ties will frequently stimulate the appet.i.te. In other words, various feeds and combinations should be given to the horse. Throughout the course of the disease and during convalescence the greatest attention must be taken to cleaning the coat thoroughly so as to keep the glands of the skin in working order, and light, warm covering must be used to protect the animal from cold or drafts of air.