Part 94

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.