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.