LUNG PLAGUE OF CATTLE.
Synonyms. Definition: infectious, cattle fever, with long incubation, insidious onset, excessive pulmonary exudation, infarctions and sequestra. History: ancient, modern; England, Norway, Sweden, Denmark, United States,—its extinction in 1887 to 1892—Massachusetts, New Jersey, S. Africa, Australia, Tasmania, New Zealand. Causes: contagion only. Bacteriology: Nocard’s organism cultivated in collodion capsules in vivo, as actively motile refrangent points, morphology uncertain. Modes of transmission, exhalations from sick inhaled by susceptible, ingestion of infected food, pastures, watering troughs, ponds, commingling of herds, attendants, dealers, stables, manure, unrestricted commerce, convalescent cattle, breed, hot seasons. Lesions: profuse exudation in lymph networks of lungs, marbling, parenchymatous cell proliferation, compression and gangrene of lobulets, thrombi, sequestra, infarction, fibroid sac, or stalactite-like fibroid peribronchial formations, hepatization, pleural effusions and false membranes, pericardial, bronchial, lymph glands congested. Incubation: 6 to 30 days, protracted cases, bearing on quarantine. Symptoms: conditions affecting gravity, breed, excitement, heat, chill, susceptibility, usually insidious, infrequent cough, roused by cold water, dusty food, exertion, etc., hurried breathing when driven, slight auscultation râles, hyperthermia (103° to 108° F.), dulness, anorexia, suppression of milk, stiffness, no pandiculation, troubled breathing, auscultation, and percussion signs of extensive consolidation, tenderness of chest walls, in bad cases stands obstinately, head extended, mouth open, tongue protruded, grunts with expiration, heavy breath, nostrils dilated, nasal and buccal discharge, rapid emaciation, fœtid diarrhœa, erect hair, pale, scurfy, adherent skin, varied chest râles, abortion. Mild in winter, severe in summer. Loss of one-third or one-half weight in one week. Chronic cases, fibroid and necrotic changes, sequestra. Diagnosis: Anamnesis, inoculation: from tuberculosis by high fever, rapid, extensive infiltration, early succession of new cases, failure to react under tuberculin, absence of tubercles; from bronchitis and pulmonary strongylosis, by the succession of cases in place of many at once, the extensive exudation, the evident cause (exposure or infected place), and by the lesions; from fibrinous pneumonia, by absence of climatic cause, the more extensive consolidation, more troubled breathing, and coexistence of old and recent lesions; from infectious pneumonia by the greater area consolidated, more exalted hyperthermia, more marked dyspnœa, the absence of white points of alveolar cell proliferation, and by the old and recent lesions; from septicæmia hæmorrhagica, by its occurrence at all seasons, on all soils, by the absence of sanguineous swellings at other parts, by the absence of cocco-bacillus from the exudate, and by its non-inoculability on sheep, horses, pigs and rodents; from needle in pericardium, by its epizoötic prevalence, fever, and the absence of preliminary gastric and later cardiac, morbid phenomena; from emphysema by the fever, absence of drumlike tympany, and presence of consolidation; from aspergillosis of the lung by the fever, more rapid progress and extended consolidation, by the harmlessness to birds, by the absence of aspergillus from expectoration and lung; from insolation by the absence of the causes of heat stroke, of the implication at once of a number of exposed animals, of the excessive hyperthermia, the brain symptoms and sudden deaths. Treatment: a poor economy, to be punished when extinction is attempted. Prevention: importation under three months quarantine, surveillance of three months more in case of single animals; applied to lung plague countries and those adjoining; disinfect cars and boats that have been used in lung plague country; exclude hay and fodder from lung plague country; also litter, bags, head ropes, horns, hoofs, hides, hair. To extirpate: stop all ingress of possibly infected cattle, stop movement of cattle, prohibit common or unfenced pasturage, kill without indemnity in case of violation, record all cattle, make necropsy of all dead, kill and pay for all infected herds, disinfect all infected premises and things, use horses in removing and plowing under manure. Unaided owner may: breed all his stock, in buying bull quarantine him, allow no intercourse between his herd and others, get new cattle from herds only that have had no illness nor losses for a year, and no exposure, and bring by thoroughly safe route, in disinfected cars or boats, then quarantine, under special attendants. Immunization; by a first attack, inoculation in tail, intravenous, of sterilized exudate. Conditions permitting and forbidding immunization.
Synonyms. Bovine Pleuro-Pneumonia, Contagious Pleuro-Pneumonia, Peripneumonie (Fr.), Lungenseuche Vieseuche (Ger.), Pneumosarcia, Peripneumonia Exudativa, Epizoötic Pleuro-Pneumonia, Pulmonary Murrain, Slijmlongziekte (Dutch), Pulmonea dei Bovina (Ital.), Phush phush pirdaho, Pheepree (Bengalee).
Definition. An infectious febrile disease, occurring casually in cattle only, so far as known, and characterized by a prolonged incubation (10 to 90 days), a tardy insidious onset, inflammation of the bronchia, lungs and pleuræ, a profuse exudation into the interlobular connective tissue and chest, a very extensive area of consolidation, pulmonary infarction, and sequestra.
History. It is difficult or impossible to identify this disease among the various animal plagues in ancient times. Yet when lesions are given it may be admitted in different cases. Aristotle, writing 350 years before Christ says “the cattle that live in herds are subject to a malady which causes the breathing to become hot and frequent. The ears droop and they cannot eat. They die rapidly and the lungs are found spoiled.” Here the facts that cattle alone suffered, that large herds suffered most, that the lungs were the seat of very marked lesions, and that fever and mortality were both marked, point forcibly toward lung plague. Valentini’s description of a fatal lung disease in cattle also stands out prominently in the obscure records. The first full and definite report is that given by Bourgelat of its prevalence in Franche-Compté in 1769. Later the records are frequent and from all over Europe, indicating its general prevalence before as well as after Bourgelat.
Much more important are its definite extensions into new countries after a long interval of immunity as showing that with trustworthy records such invasions can always be satisfactorily accounted for by the introduction of cattle or their fresh products from a previously infected area. Into Holland it was imported from Germany in 1835 by Vanderbosch a Guelderland distiller and spread over the whole country. Attempts were made in Friesland, and at first successfully, to stamp it out by slaughter and disinfection, but the demands of the trade toward England grew so enormously that it was being constantly introduced anew and the measure was abandoned. The British Consul at the Hague, in 1839 sent some Dutch cows to a friend in County Cork, Ireland, which led to the general infection of that island and indirectly of Great Britain. In 1842, under the Free Trade Act, England became at once deluged with lung plague cattle from Holland, Belgium and France on the one side, and Ireland on the other. Soon the whole island had been infected except exclusively breeding districts (Welsh and Scottish Highlands, etc.) into which no cattle were ever introduced from outside.
In 1847 an importation of English cattle into Sweden conveyed the disease, where it prevailed for some time and even infected Denmark through shipments of cattle, but was finally extirpated by the pole axe and disinfectants.
In 1860, Norway imported infected Ayrshire cattle for the Royal Agricultural College at Aas, but the imported and exposed stock were promptly destroyed and the previous immunity of the country has been maintained up to the present.
Denmark was infected in 1848 by importation from Sweden, and on different other occasions from Germany and England, but by prompt and rigid suppressive measures, stamped out the disease on each occasion. This was true also of Schleswig so long as it remained a part of Denmark, but the infection entered in the commisariat parks of the German army in 1864, and the principality remaining in German hands, the lung plague became permanently established.
Mecklenburg-Schwerin and Oldenburg also maintained vigorous suppressive measures and for long kept clear of the infection.
Into Brooklyn, lung plague was introduced in 1843 through the purchase of an English ship cow by a dairyman (Peter Dunn). From this centre the infection spread until it prevailed in Connecticut, New York, New Jersey, Rhode Island, Pennsylvania, Maryland, Virginia, District of Columbia, Ohio, Indiana and Illinois.
In 1879, measures were taken in New York and New Jersey to extirpate the disease but failed to receive the requisite continued support and were practically abandoned. It was only in 1887 when the infection had reached Chicago, the largest cattle market in the world, that the National and State Governments were aroused to the gravity of the danger, and, the Federal Government supplying the funds and the Illinois Government the authority, the beginning of a real attempt at extinction was seriously undertaken. The author acted as chief of the national veterinary force in Illinois in 1887, and takes great pleasure in recording that at the end of three months from the date of his arrival, the last acute case of the disease had been disposed of and the frightful danger that had threatened the nation through the Chicago stock yards had been removed. The supervision was maintained for a year later, and some old sequestra were later found in the lungs of cattle slaughtered, but no acute nor dangerous cases of the disease. This was followed by vigorous suppressive work in other infected states and by September, 1892, the quarantine was raised and the nation pronounced free from lung plague. The last cases were met with in New Jersey, early in 1892. In this last anti-lung-plague crusade the National Government inspected 1,605,721 cattle in 166,951 herds, made 356,404 necropsies, purchased 21,961 head of cattle, and disinfected 4,128 premises. 7,438 cattle were found affected at the necropsy.
Another line of infection was started by 4 Dutch cows, landed at Boston in 1859, and before the end of the year the infection had extended into 20 different townships in Mass. In 1860, a State Commission was created, with Dr. E. F. Thayer as veterinary commissioner, and in the next few years they destroyed 1,164 cattle, and stamped out the plague at a total cost of $77,511.07.
An importation of infected cattle into New Jersey was made in 1847, by Mr. Richardson, who on discovering the nature of the disease, made an end of that particular contagious centre, by slaughtering his whole herd at a cost of $10,000.
South Africa was infected in 1854 by the landing of a Dutch bull at Cape Town. As there were no railroads and all inland carriage was conducted by ox-wagons, it soon spread over the colonies and extended thence into the native states, and has continued to the present time.
Australia was infected in 1859 through an English cow landed at Melbourne. When the disease was identified, the whole herd was slaughtered and paid for, and the farm quarantined. But the quarantine was broken by a teamster turning his work oxen into the pastures under cover of night, and the infection escaped and has prevailed over Australia to the present day.
Later the disease extended in a similar manner, to Tasmania and New Zealand.
Causes. The one essential cause of lung plague is contagion from a preëxisting case. Before the days of bacteriology, this had been demonstrated as conclusively as any truth can be. All extensions into a new country or district could be traced to direct importation from a preëxisting area of infection. Until such importation such lands have been immune from time immemorial; at once after, the infection has spread from the imported animals as a centre; if the stock is divided up and scattered, several primary centres are formed from each of which the plague makes extension. Again, isolated islands (Channel Islands) and purely breeding districts (Scottish Highlands) into the herds of which no store cattle from outside are admitted, remain immune through centuries, no matter how prevalent lung plague may be in the countries immediately around. The immemorial immunity of the Western Continent, up to the date of the arrival of the now famous Dunn cow, the continued immunity of Canada and Mexico after the infection of the Eastern United States, and the immunity of the United States since the last infected cattle were destroyed in 1892, are equally conclusive in this respect.
Bacteriology. The history of lung plague forcibly illustrates how harmless microbes of large size, that may be easily discovered, and which existing in the environment, readily find their way into diseased and susceptible parts (in this case into the bronchia), may be held to be the pathogenic cause. Willems and Van Kempen, in 1852, found microbes in the exudate. Lustig in 1885 found four separate microbes in the lesions, 1st, a short, thick, liquefying bacillus to which he attributed the disease; and 2d, 3d, and 4th, three forms of micrococcus. Poels and Nolen, in 1886, demonstrated bacilli of variable size (0.9μ), solitary, in pairs and chains, cultivable in different media, and inoculable by injecting such cultures into the lungs, but the resulting lesions were not marked by the full lung plague exudate. Arloing, in 1887, separated from the exudate the bacillus liquefaciens bovis, a very short, slender bacillus, often in pairs with flagella, motile, staining easily in anilin but not in Gram’s solution, quickly liquefying gelatine as a culture medium and assuming a form that might be taken for micrococci, quickly obscuring peptonized bouillon, and growing on potato. The exudate placed in a thermostat at 95° F. encreases in potency. The bouillon cultures injected under the skin or into the lung, produced characteristic lesions of lung plague.
In the light of the later experiments of Nocard and Roux in 1897–8, it would appear that Arloing’s bouillon cultures were probably complex, containing not only the bacillus liquefaciens bovis, but also, the infinitesimal microbe which is the true cause of the lung plague. In seeding culture media with the exudate taken with all possible precaution against contamination, from the interlobular pulmonary connective tissue, they and others constantly failed to obtain results. Better success attended their efforts with Martin’s culture bouillon for producing diphtheritic toxin. Five pigs’ stomachs are minced, pounded to pulp, mixed as follows: stomach 200 grs., pure muriatic acid 10 grs., water 50° C., 1000 grs., left in a thermostat at 50° C. for 12 hours, (to 24), then heated to 100°C. to destroy the action of the pepsin, then lowered to 80° C., alkalized, filtered from flocculi that formed, heated to 120° C., and filtered. This is then mixed with peptonized meat juice prepared as follows: fresh beef or veal, minced and pulped, 500 grs., and water, 1 litre, are kept for 20 hours at 35° C., the liquid expressed, 5 grs. common salt added, mixed in equal proportions with the peptonized liquid from the pig’s stomach, heated to 70° C. to coagulate albuminoids, filtered, alkalized and sterilized. To this mixture is added ¹⁄₂₅th part of blood serum (sterile) from the rabbit or cow.
This bouillon was inoculated with the pulmonary interlobular exudate, enclosed in collodion capsules, having very thin walls, and inserted aseptically into the abdomen of the rabbit. In 15 days the rabbit was sacrificed, and the capsules enucleated from their envelopes of exudate and cells. The contents showed the slightest possible shade of opacity, but they contained neither cells nor any other definite organism. Under a magnifying power of 2000 diameters the liquid contents were found to be full of brilliantly refrangent points, actively mobile, but so minute that their form could not be made out even when staining was resorted to. The contents of these capsules when inoculated on cattle produced the unequivocal phenomena of lung plague infection in a period of from 8 to 15 days. Other collodion culture cases inoculated from this produced the same cultures in the peritoneum of the rabbit. Collodion cases charged with the uninoculated peptonized bouillon, and placed in the rabbit’s peritoneum remained absolutely clear, with no refrangency nor motility under high powers and with no infectivity when inoculated. The rabbits used for the infective cultures often became emaciated to the last degree and even died, but their tissues proved in no respect infecting to culture media nor when inoculated. The attempt to cultivate the germs in collodion cases in Guinea pigs completely failed.
This ingenious form of culture devised by Metchnikoff for experiments on the more delicate organisms, has been used by Nocard to accustom the tubercle bacillus of mammals to grow in the bird and opens up great possibilities for future investigators. The collodion, being impermeable to leucocytes and bacteria, allows these to grow almost together, only on the opposite sides of the collodion wall, restrains phagocytosis, and protects the microbe against the destruction which would otherwise overtake it.
Modes of transmission. The exhalations from the sick convey the infection to susceptible healthy cattle. Yet even this was denied by one veterinary teacher in Great Britain in the latter half of the 19th century. The transmission of the disease by mediate contagion was denied by those in authority in Great Britain up to the end of the century and this delusion contributed largely to the loss of many millions by the nation. Experiments made at Brown Institution were held to sustain this, but not an atom of evidence was furnished to show that the exposed animals were susceptible ones. Diseased lungs kept for a year at 21° F. proved infecting when inoculated (Laguerriere).
Contagion through the air in the same stable was admitted even by the English sceptics. It may be carried in this way for forty yards, or if dried on dust or light materials to a great distance.
Infection through food soiled by breath or nasal defluxion is a common cause. In our great swill stables during the prevalence of the plague, it was notorious that the disease advanced rapidly along the line of a feeding trough to the sixty or more animals using it, and that the rapidity of the advance was determined largely by the fact that the first animal was at the higher end of the trough. If at the lower end there was no upward current to carry infection to the others. Open pastures where the sick have fed and watering troughs or ponds are common sources of infection. The permanence of infection in and around large cities is largely due to the common pasturage by different herds in succession on the same unfenced lots waiting to be purchased for building. For this reason the plague always extended in summer when the cattle frequented these lots, and diminished in winter when they were strictly confined to stables and yards.
Mingling of different herds on great unfenced areas has been the main cause of the maintenance of the infection from time immemorial in the hills and forests of central Europe and on the boundless Steppes of Europe and Asia. This alone is chargeable with the permanence of the affection, in spite of all efforts for its extinction, in South Africa, Australia, Tasmania and New Zealand.
Contagion carried by attendants, cattle dealers and even dogs, is generally recognized, I have elsewhere quoted the case, in E. Lothian, Scotland, in which the son of the steward, who was cattleman on an infected farm, was the means of infecting first, his father’s cow, and later the whole of the stock on the place; also the case at Quincy, Mass., in which a farmer coming straight from the slaughter of sick cattle, infected his own herd; also the case of Mr. Jewell, of Long Island, who carried the infection from the herds visited, to his own family cow in a thoroughly secluded stable.
Infection through infected and emptied stables, was a common experience in dealing with the lung plague in America. Cows kept alone and only introduced after the predecessor had died habitually contracted the disease, though brought, through the most carefully guarded stockyards, from healthy districts. Stables have continued infecting for a year after having been vacated, (Friedberger and Fröhner).
Infection through manure spread on ground to which susceptible cattle had access was an occasional occurrence.
An active, unrestricted commerce is however the most prolific means of infection in cultivated countries. Slow as the disease progresses, and long as the animal diffuses infection, it soon attacks and kills or immunizes all the susceptible animals in the single herd, and if no other susceptible animal is bought or born into the herd, the germ in due time loses its pathogenic potency and infection is at an end. In this way many centres of infection started in herds on well fenced farms have worn themselves out. But the case was far otherwise in the city dairies and swill stables. The trade demanded that the stalls emptied by deaths should be filled up to consume the swill, or supply the milk route and thus fresh susceptible cattle were constantly exposed in the infected stable. The dairy cows were supplied by dealers who charged exorbitant prices for them and held a chattel mortgage for the amount. They had come through the infected dealer’s stable, and if they did not come up to the milk yield promised, they were either passed on to another dairy or returned to the dealer’s stable carrying back a new load of infection. The wagons used to carry the cows through the city were constantly infected and infecting. The swill stables became the final destination of the surviving cows that had gone dry and thus infection constantly gravitated into them.
In Europe where the great cattle and meat trade with England and the constant demand for cattle to consume the marc of the beet sugar and other factories, cause a continuous draught upon the infected districts the great western centres of enterprise and commerce have found it impossible to exterminate the plague.
In the country districts in England outbreaks were almost exclusively confined to the times when fresh cattle were purchased at one of the great fairs. Hence the late autumn, the period of laying in feeding cattle, witnessed the greatest extensions.
In Ireland, as shown by Ferguson, the whole cattle trade seemed to be arranged as if for the speedy and universal diffusion of infection. Calves, bought by jobbers from all sources, were bunched together with every opportunity for intercommunication and infection. As soon as they were a little further matured, they were assorted in lots and sent to a fair, where they were sold, and found their way to great common pastures, and this process was repeated again and again until they had reached full maturity. On the way to and from each market they were quartered over night in a public yard which had just been vacated by other animals, often diseased, traversed the same roads, and drank and fed from the same troughs which diseased ones had just used.
The introduction of apparently recovered cattle is generally credited with the infection of a fresh herd and Friedberger and Fröhner quote with approval Walley’s assertion that a recovered animal with a sequestrum in the lung can infect a herd into which it is taken. I have failed to produce even local exudate, subcutem or in the lung, from sequestra which were much more recent, but the animals operated on were rendered immune and inspired me to carry out a system of immunization by the use of the sterilized fresh exudate. The actual date of the expiration of virulence in the necrotic lung tissue has never been demonstrated and probably varies in different cases.
The receptivity of different breeds has been discussed and the Holsteins and Shorthorns have been thought to show the greatest susceptibility. These are among the cattle that are most prized, bought and sold, and exposed to infection. The Shorthorn especially has a great development of the circulatory system, including the connective tissue with its great lymph sacs and channels, and the microbe we are dealing with shows a marked preference for the lymph system, in which it finds its appropriate field of development. Susceptibility is greatly encreased by a warm climate or hot season, under which large herds may die without a single exception, the disease running a fatal course in two or three days. In cooler climates 20 per cent. will often escape at first (French Commission Experiments, 1849).
Lesions. If death has taken place early, the lesions are usually essentially pulmonary, though they may implicate the pleuræ and mediastinum. In many cases the lung alone is involved, yet even then the predilection of the microbe for the lymph network of the interlobular tissue is strongly manifested in the serous infiltration of that, rather than of the lung structure proper. This determines the much talked of marbled lung, the pulmonary lobules standing out at first as a more or less deep red brown or black, while the marbling is caused by the yellowish or grayish infiltrated tissue surrounding each pulmonary lobulette which appear set in, as in mosaic on the surface of a section. Sometimes a blood extravasation discolors the interlobular exudate as well, yet it retains its soft liquid appearance which sufficiently distinguishes it from the firmer lung tissue. These yellowish interlobular markings vary much in thickness, but in acute cases this may be up to half an inch or even more. In the lesions of longer standing the interlobular exudate has usually coagulated, or even undergone fibroid organization, so that it compresses and condenses the lobules which it surrounds.
The pulmonary lobules may show the earliest changes of the alveolar and lobular capillaries, with formation of an exudate, and an active proliferation of small round cells in and around the alveoli. Later the exudate coagulates, forming the familiar red hepatization, and this in its turn may pass into the gray, or it may liquefy and undergo absorption and resolution. Other changes are not uncommon. The excess of interlobular exudate will compress the pulmonary lobules so as to reduce their size and expel the blood from their structure, giving them a pale color, or this compression becomes still greater, completely arresting the circulation and inducing lobular gangrene. Thrombi in the afferent and efferent vessels contribute to the necrotic change, and sequestra of varying size, from that of a nut to that of an infant’s head or larger, are formed. The earliest stage of this necrosis is usually infarction of the lung, a definite area of which becomes saturated with dark blood cells so that in contrast with the rest of even the hepatized lung, it is almost as characteristic as the marbling. The further progress of this necrosis is varied. Most commonly the exudate surrounding the necrotic mass becomes organized into white fibrous tissue and forms an investing sac in the interior of which is the dead lung tissue, showing for a time distinctly, the bronchia, blood vessels, lobulettes, and interlobular tissue. This gradually becomes detached and floating in a liquid debris, slowly undergoes solution, and is absorbed, the sac meanwhile closing in on the cavity. A large sequestrum may be a year or sixteen months in undergoing complete solution. In other cases the pulmonary lobulettes undergo an individual softening while the interlobular tissue becomes organized and when cut across, the lung presents a distinct honeycombed appearance. In still other cases a considerable area of both lobulettes and interlobular tissue is necrosed and liquefied, while the exudate, around the bronchial tubes, that supplied it, becomes organized, and on the necropsy the latter are found to constitute a thick branching mass of a very characteristic appearance.
The newly affected lobulettes have a watery or gelatinoid or dropsical appearance and if freely incised give out a large amount of serum and flatten down in doing so. When hepatized the cut surface is granular, and microscopic examination shows the terminal bronchia and alveoli filled with a fibrinous exudate containing great quantities of red blood globules and leucocytes. The distension of the lung is enormous, so that when the entire organ is infiltrated it may weigh from 50 to 100 pounds.
In recent cases the lung may be extensively affected without affecting the pleuræ; in other cases both are early involved. In advanced cases the pleuræ are always implicated. First there is the subpleural infiltration over the affected part of the lung; later the pleural surface has reddened arborescent patches, with a slight solid exudate, and a yellowish (sometimes blood-stained) serum collects in the bottom of the cavity; later still the affected portion of the lung is covered more or less thickly with false membranes, while others cover the organ or the parietal pleura below this level, and hang in shreds or bind the lung to the ribs. In old standing and recovered cases these may be largely represented by dense, white fibrous investments covering the lung or the rib, or establishing permanent adhesions. The amount of pleural effusion may be about two gallons in bad cases, and like the invasion is either unilateral or bilateral. The pericardium is usually more or less involved in pleuritic cases.
The larger bronchia sometimes contain false membranes.
The bronchial, prepectoral and mediastinal lymph glands are often enlarged, congested and infiltrated with an abundant exudate.
Similar infiltration of the lymph glands of the pharynx, mesenteries. sublumbar region and groin are described, together with hypertrophy and congestion of the intestinal follicles, and congestion of the muscles and intermuscular tissue, of the articular and tendinous synovial sacs, and even of the meninges of the brain and cord. I know of no facts to show that these conditions result from anything else than the toxins and the general constitutional disorder. The indications are that the microbes are speedily destroyed in the circulating blood, and intravenous injections and caudal inoculations alike fail to cause the characteristic lesions in the lung, their favorite point of casual election.
Incubation. This usually lasts from 6 to 30 days, being greatly abridged by hot weather and often prolonged in the cold. Delamotte claims to have seen it extend to 5 months, and in one case a calf turned out on Montauk Point, L,. I., from an infected place was noticed ill on the 104th day. Australia, South Africa and Norway were each infected by cattle that had been three months out of their native infected land. I have seen cattle pass three or four months after purchase in an unthrifty condition, yet without cough or other recognized diagnostic symptom and then come down with lung plague. Such doubtless explain the alleged protracted incubations, the system has been invaded, ill health ensues, but the lungs are only slightly affected for a length of time. In other cases one animal in a herd has had a mild attack, which escaped notice, and it was only later that the disease was recognized in a second victim, infected from this first.
The bearing of this on imported animals is evident. An animal imported alone should be kept under surveillance for a month or two after quarantine, while in any considerable herd the disease would certainly manifest itself during the prescribed three months detention.
Symptoms. These vary greatly with the animal and its environment. Other things being equal it may develop more suddenly and violently in the obese Shorthorn, Angus, Hereford, Ayrshire or Dutch, and less so in the spare Brittany or Jersey. In very hot weather the attack is very sudden and severe. A chill from exposure, an attack of bronchitis or pneumonia, the excitement attendant on parturition, on travelling by rail or driving may precipitate and aggravate the seizure. Under some such conditions there may be sudden and extreme hyperthermia, rapid pulse, oppressed breathing, percussion and auscultation evidence of extensive pulmonary consolidation and death in two or three days, while the body is still plump and fat.
Individual susceptibility appears to have influence, the same stable presenting simultaneously cases of acute and fatal type and others that are slow, and insidiously progressive. In newly invaded countries and in bovine families that have not been exposed to the infection for many generations the tendency is to a higher proportion of severe and fatal cases, while in herds native to districts that have been continuously or frequently exposed, mild cases tend to predominate. The more susceptible strains of blood have been killed out, and the surviving strains show a greater power of resistance.
Apart from the predisposing environment the tendency of lung plague is to set in slowly, insidiously, and for a time almost without outward symptom. For a week, fortnight, month or more there may be a slight cough heard only at rare intervals and neither painful nor specially troublesome. Though sometimes hard, it is more commonly small, weak, short and husky, noticed only when the animal rises, drinks cold water, goes out to the cold air, or eats dusty or fibrous fodder, and is usually attended by arching of the back, extension of the head, opening of the mouth and protrusion of the tongue. For weeks there may be no indication of constitutional disorder, appetite, rumination, milking, and other functions appearing to be normal. Driving the animal may unduly accelerate the breathing, and a careful auscultation may detect an unusually loud blowing sound behind the middle of the shoulder, a mucous râle, or a wheeze. In some cases the disease never advances farther, the trouble subsides and the subject is thereafter immune. Cases of this kind occurring as the first in a herd, explain some instances of what are claimed to be specially prolonged incubations.
In the great majority of cases further symptoms appear, hyperthermia sets in, varying in different animals from 103° to 108° F., the animal becomes dull, depressed, loses in appetite, rumination and milking, omits pandiculation on rising, shows stiffness of the hind limbs, sometimes knuckles forward at the fetlocks, wanders apart from the herd, is found lying apart, shows extra thirst, bloats slightly, and shows some constipation. Pulse and breathing are accelerated, auscultation signs are more marked, and on percussion, areas of flatness may indicate lobular consolidation, usually more extended than in ordinary pneumonia with the same grade of constitutional disturbance. The muzzle becomes hot and dry, the roots of the ears and horns hot, and the hair stands erect along the dorsal aspect or in patches over the body. Pinching of the dorsal spines, sternum or intercostal spaces, may cause marked wincing and a deep groan. The eye is dull, lacking in prominence and clearness, and the lids are often partially closed. At this stage improvement sometimes ensues and after inappetence and suppression of milk for one or two days, the patient may take to feeding and milking as before, and apparently recover, though with a large pulmonary sequestrum.
In the continuous and violent cases all the symptoms are aggravated. Fever may run to its extreme height, there is complete anorexia and suspension of rumination, pulse and breathing are rapid, the victim no longer lies down but stands with feet apart, arms and elbows turned out, head extended nearly on a line with the neck, mouth open, tip of the tongue projecting, and each expiration accompanied by a moan, so loud that it may be heard at a distance (often 50 yards). The breath is heavy, feverish, mawkish. The flanks heave violently, the nostrils are widely dilated and discharge muco-purulent, often bloody liquid, strings of fœtid saliva drivel from the open mouth, there may be tympany or even colic, the eyes are sunken, and the conjunctiva and nasal and buccal mucosæ are of a dull brownish and yellowish red. Emaciation advances at a rapid rate, and the constipation may be superseded by a profuse, fœtid diarrhœa which wears out the animal. The skin is dry, scurfy, withered, pale, and clings firmly to the bones, and the interior of the vulva may show the pallor of anæmia. The spine, sternum and intercostals are more than ever tender, and pressure on the tender areas may detect a lack of movement of the lung which is felt on the healthy parts.
On percussion very extensive areas of consolidation are revealed by the dulness and flatness. If pleuritic effusion exists the resulting flatness is extreme below and up to a given horizontal level, the line of which may, however, be elevated at points by consolidation of the lung at such parts. Auscultation may reveal almost any of the abnormal sounds of pneumonia or pleurisy. Absence of respiratory murmur over large areas, with blowing, heart or abdominal sounds in unwonted situations (where the murmur is absent), and abnormally loud murmur where the lungs are still pervious; crepitation around the margins of the consolidated portions; the creaking sound of stretched false membranes, scarcely distinguishable from crepitation; mucous râles; wheezing sounds of various pitches; exceptionally splashing sounds, and if the animal has just risen, the metallic tinkling sound. In other cases the pleural friction sound is prominent.
Abortions are common in pregnant animals.
Course. This varies greatly. In our northern states in winter, many would seem to recover after a few days illness; in summer, many died in a few days with excessive exudate, dyspnœa, and prostration. Others died early from tympany of the rumen. In others still, profuse, fœtid, colliquative scouring led to an early death. In extreme cases there would be a loss of one-third or one-half the weight in a single week. In the less rapidly fatal cases all the symptoms became aggravated, the emaciation progressed, and a liquid pultaceous condition of the bowels continued for two, three, four, or even six weeks, the animal finally dying in a state of marasmus. In such cases the shrunken, pallid skin and mucosæ bespoke an extreme degree of anæmia.
Recoveries may take place from comparatively advanced stages, but they are liable to be slow and imperfect, the animal remaining unthrifty for a length of time. In some of the more favorable cases, when the recovery is less interrupted or retarded, fattening may take place rapidly, so that it would appear as if the loss of a portion of lung, and the lessened consumption of hydrocarbonaceous matter contributed to the deposition of fat.
In some cases the active morbid processes subside, but are not quite arrested and the malady assumes a chronic form, the exudates become organized, causing a sclerotic or fibroid condition of the lung and especially of the interlobular tissue, which compresses and carnifies the lung tissue, or leads to necrotic changes and the formation of sequestra, or again to liquefaction and the formation of vomicæ. Here the proliferation of the germ may go on, though little new tissue is invaded, and the animal may remain infecting for a long period. The patient remains thin, and weak, is easily blown under exercise, has a small, accelerated pulse, little power of digestion or assimilation, shows frequent tympanies, and may have profuse diuresis or diarrhœa. The cough is frequent, often paroxysmal, easily roused, loose, mucous, painful and may be attended by muco-purulent discharge. Such animals are liable to die in the end in marasmus.
In some cases the malady is complicated by other infections, leading to the formation of abscesses in the lungs, pleuræ, chest walls, bronchial glands, joints or elsewhere, or tuberculous deposits may complicate the lung plague, and there may be an early death or a long drawn out decline.
Diagnosis. So many different affections resemble lung plague closely during life, that a certain means of diagnosis is a great desideratum. Yet many points help one to reach a reasonably certain diagnosis:
1. Does lung plague exist in the country? If not the presumption is very strongly against it.
2. Have the suspected animals been recently imported from a lung plague infected country? or have they been in contact with animals recently imported from such a country?
3. Have they been fed on provender imported from such a country?
4. Have they been attended by a man recently from such a country and whose clothes have not been sterilized?
5. Have they been carried on any imperfectly disinfected car or ship which has carried the cattle of such country?
6. Has the affection attacked a considerable proportion of the herd at the same time? A rare thing with lung plague.
7. Has the attack come on slowly and insidiously? Very characteristic of lung plague.
8. Has hyperthermia been marked? Indicative of lung plague.
9. Have a succession of cases occurred at intervals of several days or weeks, irrespective of weather? Suggestive of lung plague.
10. Have the indications of consolidated lung been early and over extensive undivided areas? Like lung plague.
11. Have cases been milder in cold dry weather and more violent in hot and moist? Such is lung plague.
12. Does the same subject present lung lesions of very different ages;—infiltration with tough, elastic lung; red hepatization; gray hepatization; black infarction; sequestra, etc.? Bespeaks lung plague.
13. Do the infiltration and red hepatization show a marbling with very extensive filling and turgidity of the interlobular and subpleural connective tissue, and abundant effusion into the chest? This is the nature of lung plague.
14. Does the lung exudate when inoculated in the tail of a susceptible bovine animal (one that has never had the disease), produce local inflammation and exudation and procure immunity? This characterizes lung plague. Does it fail to cause inoculation swelling, in an animal that had lung plague. Lung plague is still more indicated.
15. If the disease has lasted long enough in a place to determine, has it affected any other than bovine animals, and does inoculation of the lung exudate into any other genus of animal cause the disease? Other genera are immune from lung plague.
Tuberculosis is distinguished by the habitual absence of the high temperature, the numerous circumscribed areas of flatness with wheezing or other abnormal lung sounds, in the midst of a general field giving the normal respiratory murmur, by the enlargement or induration of superficial lymph glands, by the response to the tuberculin test, and by the lung tubercles and diseased lymph glands,—congested, indurated, caseated, calcified—found at the necropsy. Inoculation of other genera causes tuberculosis.
Simple bronchitis is usually connected with climatic change or exposure, tends to affect a number at once, gives the blowing and mucous râles, without indications of extended lung consolidation or pleural effusion, and after death does not furnish lesions of all ages, recent and remote.
Verminous bronchitis, attacks the young only or mainly, and never seriously injures the mature, involves all or nearly all the young in the herd, shows less hyperthermia, and less extensive consolidation, more wheezing in the lungs, and a free expectoration in which the worms (embryos or adults) may be found by careful search.
Simple fibrinous pneumonia is likely to arise from climatic conditions or from exposure, attacks several at once and none later, has less abrupt rise of temperature, less tenderness of the chest walls, less dyspnœa, less obstinate standing, and after death, less interlobular exudate and marbling, and no presentation of old and recent lesions in the same lung.
In the infectious pneumonia occasionally seen in western cattle, the distinction must be made mainly by the less elevated temperature, less dyspnœa, the lack of the early signs of extensive consolidation of the affected lung, and after death, absence of the extensive interlobular infiltration, and in the predominance of the whitish points or mottling indicating the broncho-pneumonia and the cell proliferation in the terminal bronchia and alveoli.
The pulmonary form of hæmorrhagic septicæmia (Wildeseuche) is distinguished by its enzoötic character, in connection with wet lands, its occurrence in the summer season, its association with other forms of localization, in the abdomen, muscular system, etc., its dependence on a cocco-bacillus, easily found in the exudate, and its inoculability on the smaller ruminants, horses, pigs and rodents.
The perforation of lungs and heart by a sharp pointed foreign body from the reticulum, occurs sporadically in one animal which has usually been kept indoors; it shows as a rule less fever, may be preceded by tympany or other gastric trouble, shows a line of consolidation from the reticulum forward, is earlier or later complicated by morbid heart sounds or rhythm, and commonly shows a pitting swelling beneath and beside the sternum.
Pulmonary emphysema is sporadic only, usually devoid of sudden hyperthermia, or constitutional disorder, has a dry paroxysmal cough, wheezing sounds on auscultation, and a drumlike sound on percussion. If associated with bronchitis or pneumonia and attendant fever, the case is more equivocal.
Aspergillosis of the Lung usually advances more slowly, in the comparative absence of sudden hyperthermia, shows more limited areas of consolidation, less dyspnœa, and usually affects smaller animals (birds) as well. At the necropsy the presence of aspergillus in bronchia and lung tissue is conclusive.
The acute pulmonary congestion of heat stroke is sufficiently identified by the conditions under which it occurs, its sudden and rapid progress, the implication of the brain, and its occurrence in other animals similarly exposed.
Such conditions as atelectasis, pulmonary actinomycosis, distomatosis, or echinococcus, the congestion of mercurialism, etc., should be readily recognized by the attendant conditions, analysis or necropsy.
Attempts have been made to diagnose lung plague by securing a reaction, local or general, as the result of injection of the sterilized lung exudate or cultures, but they have proved eminently unreliable. The susceptibility of the serum to change under manipulation, the existence of hyperthermia before the injection, and the disposition to local infiltration under the lung plague poison are apparently insuperable obstacles.
Treatment. No treatment has been devised that would warrant the preservation of the infected animals when the alternative of prevention is available. The question is an economic one, and with a disease that is so insidious, with such a long incubation, with so many occult and chronic cases liable to escape observation and recognition, and with such a constant and prolonged exhalation from the lungs of the virulent material and the certainty almost of the diffusion and preservation of the latter, no more suicidal policy could be adopted than the preservation and treatment of the sick.
If allowed at all, treatment should be conducted in an isolated locality, well secluded from visitors and wandering animals including birds, and under the most intelligent antisepsis. It should proceed on general principles according to the individual manifestations of the disease, and might include serum therapy from immunized animals.
Prevention. For a country like the United States, now happily free from the lung plague infection, the important object is its permanent exclusion. For this the federal quarantine for three months now in force ought to be effective. The only question would be in the case of small importations of one or two animals, which might introduce infection under an apparently prolonged incubation, or with a chronic type of the disease. Small importations of one or two, might be dismissed at the end of three months quarantine under a ticket of leave system, under which they and the herd into which they are taken can be kept track of for three months more. In the larger imported herds the possibility of the escape of infection under a three months quarantine is so infinitesimal that it may be practically ignored.
Similar precautions must be taken against the importation of cattle from a country reputed to be free from the lung plague, but which imports cattle from an infected country without imposing the three months’ quarantine.
The use, for transportation of cattle from one part of an immune country into another, of cars or boats which have been used for transporting cattle in an infected country can only be permitted after the vehicles in question have been thoroughly cleansed and disinfected and attested so by the official experts.
The landing in an uninfected country of hay, fodder, or cattle-food of any kind, or of litter, grain bags, head ropes, manure, or other article coming from an infected country must be prohibited until such article shall have been thoroughly disinfected.
Horns, hoofs, hides, hair and other products introduced into the country must be disinfected. The treatment adopted to exclude anthrax would be amply sufficient for lung plague.
Measures to Extirpate the Infection. Stop all accessions of possibly infected cattle from outside. Proclaim the infected area, prohibiting all entrance and egress of cattle, and all movement of cattle from herd to herd within the area, except under special license, based on the soundness of each herd for six months antecedent. Prohibit absolutely the pasturage of cattle on public highways and unfenced or insufficiently fenced places. Send to instant slaughter cattle found in such places in violation of this rule. Make an accurate census, with individual description of each bovine animal in the infected district, and make a necropsy of each such animal dying at the hands of the butcher or casually. Hold the owner guilty of a misdemeanor with heavy penalty, for every bovine animal that goes amissing in the infected district without official post mortem examination. When an infected animal is found in a herd have the whole herd, marked, appraised slaughtered under official supervision and with necropsy of each animal. If any herd has been losing animals, or had sick animals within a year, buy and kill the whole herd. Indemnify the owners to the amount of at least two thirds or three fourths of the sound market value for all except the advanced and acute cases of the disease, and such animals as have been moved into the State less than three months before. These latter may be sacrificed without indemnity. Disinfect thoroughly all infected premises and things at public expense. Close the fields against all outside cattle for three months. Burn all hay, straw, litter, and grain in the infected buildings or see that they be fed to horses, sheep or pigs apart from where cattle are kept. Burn or disinfect all manure or have it drawn out and plowed under by horses, and the wagons and implements used in doing so thoroughly disinfected. Allow restocking of the disinfected premises from sound districts only, and keep up the strictest supervision and control of the herds for from three to six months.
For private Control in the absence of Government Action. The stockowner in a secluded locality, not bordering on a highway or railway can as a rule secure the immunity of his herd by such measures as the following. Breed all the stock on the farm. If a change of blood is required buy the bull young and keep him strictly by himself for at least four months, allowing him to mingle with other cattle only after he has been thoroughly attested. Allow no animals to go outside for service or any other purpose and afterward return to the herd. Allow none to enter from without for any such purpose. If from any cause cattle must be bought, secure them from healthy herds and transport them in thoroughly disinfected cars, boats and by healthy roads, and never through an infected district. Place them in special premises at least one hundred paces from all other cattle, and under special attendants for three months.
Immunizing through a First Attack. When lung plague was at its worst in Great Britain, Mr. Harvey a dairyman on a large scale in Glasgow practiced the method of buying heifer calves and exposing them in his infected stables until they contracted the disease. He had a loss of 20 per cent. and the surviving 80 per cent. were then turned out on his farm and raised and when they came in milk, were sent into Glasgow as new milch cows immunized from the plague. He thus reduced his losses to the minimum of one fifth of the inexpensive calves, and warded off the heavy losses previously sustained in the valuable milch cows and preserved the still more valuable trade in the milk of healthy animals. The method was a mere temporary makeshift, depending for its success on the permanent maintenance of the lung plague, but so long as there were no well considered government measures for its extinction its permanence was assured in any case, and Mr. Harvey was working no injury to any one, while he was substituting a profitable occupation for a losing one, and supplying his customers with milk from sound cows in place of those that were continually coming down with the plague. Under official measures for the plague-extinction his attempt would have been most reprehensible, but in the absence of such measures it was highly meritorious.
Inoculation in the Tip of the Tail. This is an advance and in some respects an improvement on the Harvey system, as the infection and lesions are localized in the tail, and the mortality is reduced to 2 per cent. In practice a recently attacked animal is selected, and a portion of the lung which is strongly infiltrated but not yet hepatized. This is laid upon a clean scalded plate and incised with a clean scalded knife when an abundance of a clear yellow serum drains out. This is drawn up into a sterilized hypodermic syringe, and the tails having been washed and sterilized, the nozzle is inserted under the skin of each in succession and a drop or two of the liquid discharged subcutem. If despatch is important the washing may be dispensed with and the nozzle wiped and dipped in strong carbolic acid between each two successive insertions.
Various modifications of this procedure have been made. To avoid the inevitable entrance of ærial germs, flamed pipettes have been inserted into a puncture in the turgid lung, made with a flamed knife, the point is then broken and the serum is drawn up to fill the vacuum caused by the heat employed in sterilization. The point is then sealed by melting the glass in the flame of an alcohol lamp, or by melted wax.
Nocard washed the surface of the infiltrated or hepatized lung with boiled water, then with a sterilized knife cut out a deep segment so as to leave a conical cavity and covered this with an awning to keep off dust. The space soon fills with the draining exudate in a very pure condition.
Pasteur inoculated a calf in the dewlap or behind the elbow, where an enormous engorgement forms, involving the whole ventral aspect, and supplying an almost unlimited amount of serum, which may be collected with such precautions against contamination as are indicated above. The product is thus secured at a comparatively cheap rate, and the risk of its diffusion on the air in breathing is lessened enormously.
Another method is to employ the serum from the swellings in the inoculated tails and carry it on indefinitely from tail to tail.
Arloing in his turn employed the cultures in vitro of his pneumo-bacillus, but with the modern evidence that this is not the infective germ, such cultures can not always be implicitly relied on.
In place of the hypodermic syringe, Australians have used a simple thread soaked in the exudate and drawn through beneath the skin. Others have used a small lancet with a groove hollowed out in the middle of the flat surface of the blade on one side, and which carries in the required drop of the serum.
To preserve the exudate for some time against decomposition, it has been kept on ice, or mixed with chloral hydrate or phenic acid (½ its volume), and glycerine (½ its volume) for two or three months.
Injection into the veins practiced by Burdon-Sanderson has the advantage of producing no local lesion whatever and yet securing a fair measure of immunity. It is, however, a much more delicate operation as it entails a possible though remote possibility of producing capillary thrombi, and some danger of infection of the wound in the vein. To avoid this latter, the jugular vein is raised as for phlebotomy, and a short needle is passed into it. A longer and more delicate needle is now passed through this, and the injection of a few drops of the exudate is made through the latter. The small needle is then carefully withdrawn to be followed a few seconds later by the large.
Injection of the Sterilized Exudate Subcutem. In 1881 having found that liquids obtained from old sequestra, produced no local lesions when inoculated subcutem, but secured immunity for the subjects, I inoculated ten susceptible cattle with the fresh pulmonary exudate which had just been heated for 30 minutes to 180° F. No local inflammation nor exudate occurred in any of them, but subsequent inoculations with fresh unsterilized lung plague exudate were resisted in the same way. Six of these immunized cattle were subsequently placed in two infected stables and herds, (Mr. Butts, Brooklyn, N. Y., and Mr. Christopher Slade, White Hall, Baltimore Co., Md.) and retained there for three months without showing the slightest indication of disease. Later I applied the measure on a number of herds with thoroughly satisfactory results. About ten years later a similar resort was had by Arloing and Rossignol with corresponding success.
Two advantages come from this method: 1st, there is no local infection and no marked swelling so that the injection can be made on the side of the neck where the skin is thin, and clean, and the connective tissue abundant, and where there is less risk of extraneous infection than in the too often dirty or filth soaked tail; 2d, as no living germ is introduced there is no possibility of propagating the disease to other neighboring susceptible animals. Two per cent. of loss, of animals inoculated by the Willem’s method is counted on, but with the sterilized virus there is not even a remote probability of loss. Infection cannot occur from the animal injected with the sterilized virus, so that it can be safely applied among cattle that have not been exposed to infection, but which are likely to be in the future, and these injected cattle can be left to mingle with others that have not been injected without a shadow of danger to either.
Conditions permitting and forbidding Immunization. Immunization is permissible or commendable in all cases in which lung plague is already widely spread in a land destitute of fences and in which cattle roam at large, and herd mingles freely with herd. Here the extension of the disease is inevitable and continuous and effective measures for extinction are impossible. It is permissible where the plague is widely spread among cultivated and fenced farms, but where no authoritative measures are in force for its extinction. In such case, with the Willem’s system the inoculated herd should be kept thoroughly secluded in premises or well fenced pastures, apart from any highway, and not adjoining any other cattle pasture.
When on the other hand official measures are in force for the extinction of lung plague, every form of immunization based on the production of the pathogenic germ in the living body of the bovine, or even in vitro, is to be unqualifiedly condemned. The risk of the escape of the infection through subtle, unsuspected channels is too great to allow of its reproduction in any form. By restriction of cattle movement, slaughter and disinfection, extinction of lung plague is easy and certain, but, whatever may be true of an individual herd, no country has ever permanently extinguished lung plague infection, when the virus was systematically multiplied for uses in inoculation.