Chapter 18

"This first stage of the disease sometimes continues during a month, or more, and then, if the animal is to recover, or at least, apparently so, the symptoms gradually disappear. First of all, the appetite returns, and the beast begins to acquire a little flesh. The proprietor should then make haste and get rid of him; for it is very rare that the malady, however it may be palliated for a while, does not reappear with greater intensity than before.

"In most cases, the disease continues to pursue its course toward its termination without any remission,--every symptom gradually increasing in intensity. The respiration becomes more painful; the head is more extended; the eyes are brilliant; every expiration is accompanied with a grunt, and by a kind of puckering of the angles of the lips; the cough becomes smaller, more suppressed, and more painful; the tongue protrudes from the mouth, and a frothy mucus is abundantly discharged; the breath becomes offensive; a purulent fluid of a bloody color escapes from the nostrils; diarrhoea, profuse and fetid, succeeds to the constipation; the animal becomes rapidly weaker; he is a complete skeleton, and at length he dies.

"Examination after death discloses slight traces of inflammation in the intestines, discoloration of the liver, and a hard, dry substance contained in the manyplus. The lungs adhere to the sides and to the diaphragm by numerous bands, evidently old and very firm. The substance of the lungs often presents a reddish-gray hepatization throughout almost its whole extent. At other times, there are tubercles in almost every state of hardness, and in that of suppuration. The portion of the lungs that is not hepatized is red, and gorged with blood. Besides the old adhesions, there are numerous ones of recent date. The pleura is not much reddened, but by its thickness in some points, its adhesion in others, and the effusion of a serous fluid, it proves how much and how long it has participated in the inflammatory action. The trachea and the bronchia are slightly red, and the right side of the head is gorged with blood.

"In a subject in which, during life, I could scarcely feel the beating of the heart, I found the whole of the left lobe of the lungs adhering to the sides, and completely hepatized. In another, that had presented no sign of disease of the chest, and that for some days before his death vomited the little fodder which he could take, the whole of that portion of the oesophagus that passed through the chest was surrounded with dense false membranes, of a yellowish hue, ranging from light to dark, and being in some parts more than an inch in thickness, and adhering closely to the muscular membrane of the tube, without allowing any trace to be perceived of that portion of the mediastinal pleura on which this unnatural covering was fixed and developed.

"The cattle purchased in Franche Comté are brought to Avesnes at two periods of the year--in autumn and in the spring. Those which are brought in autumn are much more subject to the disease than those which have arrived in the spring; and it almost always happens that the years in which it shows itself most generally are those in which the weather was most unfavorable while the cattle were on the road. The journey is performed by two different routes,--through Lorraine and through Champagne,--and the disease frequently appears in cattle that have arrived by one of these routes. The manner in which the beasts are treated, on their arrival, may contribute not a little to the development of the malady. These animals, which have been driven long distances in bad weather, and frequently half starved, arrived famished, and therefore the more fatigued, and some of them lame. Calculating on their ravenous appetite, the graziers, instead of giving them wholesome food, make them consume the worst that the farm contains,--musty and mouldy fodder; and it is usually by the cough, which the eating of such food necessarily produces, that the disease is discovered and first developed.

"Is chronic pleuro-pneumonia contagious? The farmers believe that it is, and I am partly of their opinion. When an animal falls sick in the pasture, the others, after his removal, go and smell at the grass where he has lain, and which he has covered with his saliva, and, after that, new cases succeed to the first. It is true that this fact is not conclusive, since the disease also appears in a great number of animals that have been widely separated from each other. But I have myself seen three cases in which the cattle of the country, perfectly well before, have fallen ill, and died with the same symptoms, excepting that they have been more acute, after they have been kept with cattle affected with this disease. This circumstance inclines me to think that the disease is contagious; or, at least, that, in the progress of it, the breath infects the cow-house in which there are other animals already predisposed to the same disease. I am induced to believe that most of the serious internal diseases are communicated in this manner, and particularly those which affect the organs of respiration, when the animals are shut up in close, low, and badly-ventilated cow-houses." [_Rec. de Méd. Vét. Mai, 1833._]

No malady can be more terrible and ruinous than this among dairy-stock; and its spread all over the country, together with its continuance with scarcely any abatement, must be attributed to the combination of various causes. The chief are: _first_, the very contagious or infectious nature of the disorder; _second_, inattention on the part of Government to the importation and subsequent sale of diseased animals; and, _third_, the recklessness of purchasers of dairy or feeding cattle.

This disease may be defined as an acute inflammation of the organs of the chest, with the development of a peculiar and characteristic poison, which is the active element of infection or contagion. It is a disease peculiar to the cattle tribe, notwithstanding occasional assertions regarding observations of the disease among horses, sheep, and other animals,--which pretended observations have not been well attested.

The infectious, or contagious nature of this virulent malady is incontestibly substantiated by an overwhelming amount of evidence, which cannot be adduced at full length here, but which may be classified under the following heads: _first_, the constant spreading of the disease from countries in which it rages to others which, previously to the importation of diseased animals, had been perfectly free from it. This may be proved in the case of England, into which country it was carried in 1842, by affected animals from Holland. Twelve months after, it spread from England to Scotland, by means of some cattle sold at All-Hallow Fair, and it was only twelve months afterward that cattle imported as far north as Inverness took the disease there. Lately, a cow taken from England to Australia was observed to be diseased upon landing, and the evil results were limited to her owner's stock, who gave the alarm, and ensured an effectual remedy against a wider spread. Besides, the recent importation of pleuro-pneumonia into the United States from Holland appears to have awakened our agricultural press generally, and to have convinced them of the stubborn fact that our cattle have been decimated by a fearfully infectious, through probably preventable, plague. A letter from this country to an English author says: "Its (pleuro-pneumonia's) contagious character seems to be settled beyond a doubt, though some of the V.S. practitioners deny it, which is almost as reasonable as it would be to deny any other well-authenticated historic fact. Every case of the disease is traceable to one of two sources; either to Mr. Chenery's stock in Belmont (near Boston, Massachusetts), into which the disease was introduced by his importation of four Dutch cows from Holland, which arrived here the 23d of last May; or else to one of the three calves which he sold to a farmer in North Brookfield, Massachusetts, last June."

_2dly._ Apart from the importation into countries, we have this certain proof--to which special attention was drawn several years ago--that cattle-dealers' farms, and public markets, constitute the busy centres of infection. Most anxious and careful inquiries have established the proposition that in breeding-districts, where the proprietors of extensive dairies--as in Dumfries, Scotland, and other places--abstain from buying, except from their neighbors, who have never had diseases of the lungs amongst their stock, pleuro-pneumonia has not been seen. There is a wide district in the Vicinity of Abington, England, and in the parish of Crawford, which has not been visited _by_ this plague, with the exception of two farms, into which market-cattle had been imported and thus brought the disease.

_3dly._ In 1854 appeared a Report of the Researches on Pleuro-Pneumonia, by a scientific commission, instituted by the Minister of Agriculture in France. This very able pamphlet was edited by Prof. Bouley, of Alfort, France. The members of the commission belonged to the most eminent veterinarians and agriculturists in France. Magendie was President; Regnal, Secretary; besides Rayer, the renowned comparative pathologist; Yvart, the Inspector-General of the Imperial Veterinary Schools; Renault, Inspector of the Imperial Veterinary Schools; Delafond, Director of Alfort College; Bouley, Lassaigne, Baudemont, Doyére, Manny de Morny, and a few others representing the public. If such a commission were occasionally appointed in this country for similar purposes, how much light would be thrown on subjects of paramount importance to the agricultural community!

Conclusions arrived at by the commission are too important to be overlooked in this connection. The reader must peruse the Report itself, if he needs to satisfy himself as to the care taken in conducting the investigations: but the foregoing names sufficiently attest the indisputable nature of the facts alluded to.

In instituting its experiments, the commission had in view the solving of the following questions:--

_1stly._ Is the epizoötic pleuro-pneumonia of cattle susceptible of being transmitted from diseased to healthy animals by cohabitation?

_2dly._ In the event of such contagion's existing, would all the animals become affected, or what proportion would resist the disease?

_3dly._ Amongst the animals attacked by the disease, how many recover, and under what circumstances? How many succumb?

_4thly._ Are there any animals of the ox species decidedly free from any susceptibility of being affected from the contagion of pleuro-pneumonia?

_5thly._ Do the animals, which have been once affected by a mild form of the disease, enjoy immunity from subsequent attacks?

_6thly._ Do the animals, which have once been affected by the disease in its active form, enjoy such immunity?

To determine these questions, the commission submitted at different times to the influence of cohabitation with diseased animals forty-six perfectly healthy ones, chosen from districts in which they had never been exposed to a similar influence.

Of these forty-six animals, twenty were experimented on at Pomeraye, two at Charentonneau, thirteen at Alfort, and eleven, in the fourth experiment, at Charentonneau.

Of this number, twenty-one animals resisted the disease when first submitted to the influence of cohabitation, ten suffered slightly, and fifteen took the disease. Of the fifteen affected, four died, and eleven recovered. Consequently, the animals which apparently escaped the disease at the first trial amounted to 45.65 per cent., and those affected to 21.73 per cent. Of these, 23.91 per cent. recovered, and 8.69 per cent. died. But the external appearances in some instances proved deceptive, and six of the eleven animals of the last experiment, which were regarded as having escaped free, were found, on being destroyed, to bear distinct evidence of having been affected. This, therefore, modifies the foregoing calculations, and the numbers should stand thus:--

15 enjoy immunity, or 32.61 per cent. 10 indisposed, " 21.73 " 17 animals cured, " 36.95 " 4 dead, " 8.98 "

Of the forty-two animals which were exposed in the first experiments at Pomeraye and Charentonneau, and which escaped either without becoming affected, or recovering, eighteen were submitted to a second trial; and of these eighteen animals, five had, in the first experiment, suffered from the disease and had recovered; five had now become affected; and four had been indisposed. The four animals submitted to the influence of contagion a third time, had been affected on the occasion of the first trial. None of the eighteen animals contracted the disease during these renewed exposures to the influence of contagion.

From the results of these experiments, the commission drew the following conclusions:--

_1stly._ The epizoötic pleuro-pneumonia is susceptible of being transmitted from diseased to healthy animals by cohabitation.

_2dly._ All the animals exposed do not take the disease; some suffer slightly, and others not at all.

_3dly._ Of the affected animals, some recover and others die.

_4thly._ The animals, whether slightly or severely affected, possess an immunity against subsequent attacks.

These are the general conclusions which the commission deemed themselves authorized to draw from their experiments. The absolute proportion of animals which become affected, or which escape the disease, or of those which die and which recover, as a general rule, cannot be deduced from the foregoing experiments, which, for such a purpose, are too limited. The commission simply state the numbers resulting from their experiments. From these it transpires that forty five of the animals became severely affected with pleuro-pneumonia, and twenty-one per cent. took the disease slightly, making the whole sixty-six per cent. which were more or less severely attacked. Thirty-four per cent. remained free from any malady. The proportion of animals which re-acquired their wonted appearance of health amounted to eighty-three per cent., whereas seventeen per cent. died. Many minor points might be insisted on, but it is sufficient here to say, that the most careful analysis of all facts has proved to practical veterinarians, as well as to experienced agriculturists, and must prove to all who will calmly and dispassionately consider the point, that pleuro-pneumonia is pre-eminently an infectious, or contagious disease.

_Symptoms._--From the time that an animal is exposed to the contagion to the first manifestation of symptoms, a certain period elapses. This is the period of incubation. It varies from a fortnight to forty days, or even several months. The first signs, proving that the animal has been seized, can scarcely be detected by any but a professional man; though, if a proprietor of cattle were extremely careful, and had pains-taking individuals about his stock, he would invariably notice a slight shiver as ushering in the disorder, which for several days, even after the shivering fit, would limit itself to slight interference in breathing, readily detected on auscultation. Perhaps a cough might be noticed, and that the appetite and milk-secretion diminished. The animal becomes costive, and the shivering fits recur. The cough becomes more constant and oppressive; the pulse full and frequent, usually numbering about eighty per minute at first, and rising to upwards of one hundred. The temperature of the body rises, and all the symptoms of acute fever set in. A moan, or grunt, in the early part of the disease indicates a dangerous attack, and the _alae nasi_ (cartilages of the nose) rise spasmodically at each inspiration; the air rushes through the inflamed windpipe and bronchial tubes, so as to produce a loud, coarse respiratory murmur; and the spasmodic action of the abdominal muscles indicates the difficulty the animal also experiences in the act of expiration. Pressure over the intercostal (between the ribs) spaces, and pressing on the spine, induce the pain so characteristic of pleurisy, and a deep moan not infrequently follows such an experiment. The eyes are bloodshot, mouth clammy, skin dry and tightly bound to the subcutaneous textures, and the urine is scanty and high-colored.

Upon auscultation, the characteristic dry, sonorous _râle_ of ordinary bronchitis may be detected along the windpipe, and in the bronchial tubes. A loud sound of this description is, not infrequently, detected at the anterior part of either side of the chest; whilst the respiratory murmur is entirely lost, posteriorly, from consolidation of the lungs. A decided leathery, frictional sound is detected over a considerable portion of the thoracic surface. As the disease advances, and gangrene, with the production of cavities in the lungs, ensues, loud, cavernous _râles_ are heard, which are more or less circumscribed, occasionally attended by a decided metallic noise. When one lobe of the lungs is alone affected, the morbid sounds are confined to one side, and on the healthy side the respiratory murmur is uniformly louder all over.

By carefully auscultating diseased cows from day to day, interesting changes can be discovered during the animal's lifetime. Frequently, the abnormal sounds indicate progressive destruction; but, at other times, portions of the lungs that have been totally impervious to air, become the seat of sibilant _râles_, and gradually, a healthy respiratory murmur proves that, by absorption of the materials which have been plugging the tissues of the lungs, resolution is fast advancing. Some very remarkable cases of this description have been encountered in practice.

Unfortunately, we often find a rapid destruction of the tissues of the lungs, and speedy dissolution. In other instances, the general symptoms of hectic, or consumption, attend lingering cases, in which the temperature of the body becomes low, and the animal has a dainty appetite, or refuses all nourishment. It has a discharge from the eyes, and a fetid, sanious discharge from the nose. Not infrequently, it coughs up disorganized lung-tissue and putrid pus. Great prostration, and, indeed, typhus symptoms, set in. There is a fetid diarrhoea, and the animal sinks in the most emaciated state, often dying from suffocation, in consequence of the complete destruction of the respiratory structures.

_Post mortem_ appearances.--In acute cases, the cadaverous lesions chiefly consist in abundant false membranes in the trachea, or windpipe, and closure of the bronchial tubes by plastic lymph. The air-vesicles are completely plugged by this material, and very interesting specimens may be obtained by careful dissection, in the shape of casts of the bronchial tubes and air-vesicles, clustered together like bunches of grapes. On slicing the lungs in these cases, hepatization is observed, presenting a very peculiar appearance, which is, in a great measure, due to the arrangement of the lung-tissue in cattle. The pulmonary lobules are of a deep-red or brown color, perfectly consolidated, and intersected or separated, one from the other, by lighter streaks of yellowish-red lymph, occupying the interlobular, areolar tissue. In the more chronic cases, the diseased lobes and lobules are found partly separated from the more healthy structures.

This occurs from gangrene, and putrefactive changes, or in some instances, from the ulcerative process, so constantly observed in the segregation of dead from living tissues. Abscesses are not infrequently found in different parts of the lungs. Sometimes circumscribed, at others connected with bronchial tubes, and not infrequently communicating with the pleural cavity. True empyema is not often seen; but, at all times, the adhesions between the costal and visceral pleura are extensive, and there is much effusion in the chest. In dressed carcasses of cows that have been slaughtered from pleuro-pneumonia, even though the disease has not been far advanced, it will be found that the butcher has carefully scraped the serous membrane off the inner surface of the ribs, as it would otherwise be impossible for him to give the pleura its healthy, smooth aspect, from the firm manner in which the abundant false membranes adhere to it. The diseased lungs sometimes attain inordinate weight. They have been known to weigh as much as sixty pounds.

_Treatment._--The veterinary profession is regarded by many who have sustained heavy losses from pleuro-pneumonia, as deeply ignorant, because its members cannot often cure the disease. Persons forget that there are several epidemics which prove equally difficult to manage on the part of the physician, such as cholera, yellow fever, etc. The poison in these contagious, epizoötic diseases is so virulent that the animals may be regarded as dead from the moment they are attacked. Its elimination from the system is impossible, and medicine cannot support an animal through its tardy, exhausting, and destructive process of clearing the system of so potent a virus. All antiphlogistic means have failed, such as blood-letting and the free use of evacuants. Derivatives, in the form of mustard-poultices, or more active blisters, are attended with good results. Stimulants have proved of the greatest service; and the late Prof. Tessona, of Turin, strongly recommended, from the very onset of the disease, the administration of strong doses of quinine. Maffei, of Ferrara, states that he has obtained great benefit from the employment of ferruginous tonics and manganese in the very acute stage of the malady, supported by alcoholic stimulants. Recently, the advantages resulting from the use of sulphate of iron, both as a preventive and curative, have been exhibited in France. It would appear that the most valuable depurative method of treatment yet resorted to is by the careful use of the Roman bath. Acting, like all other sudorifics in cases of fever and blood diseases, it carries off by the skin much of the poison, without unduly lowering the vital powers.

_Prevention._--The rules laid down in Denmark, and indeed in many other places, appear the most natural for the prevention of the disease. If they could be carried out, the disease must necessarily be stopped; but there are practical and insuperable difficulties in the way of enforcing them. Thus, a Dr. Warneke says, prevention consists in "the avoidance of contagion; the slaughter of infected beasts; the prohibition of keeping cattle by those whose cattle have been slaughtered, for a space of ten weeks after the last case occurring; the disinfection of stalls vacated by slaughtering; the closing of infected places to all passing of cattle; especial attention to the removal of the dung, and of the remains of the carcasses of slaughtered beasts; and, finally, undeviating severity of the law against violators."

Dr. Williams, of Hasselt, suggested and carried out, in 1851, the inoculation of the virus of pleuro-pneumonia, in order to induce a mild form of the disease in healthy animals, and prevent their decimation by the severe attacks due to contagion. He met with much encouragement, and perhaps more opposition. Didot, Corvini, Ercolani, and many more accepted Dr. Williams's facts as incontestable, and wrote, advocating his method of checking the spread of so destructive a plague.