microbic invasion occurs from inoculation probably either through abrasions
of the skin or by injury to the mucous membranes from coarse fodder, etc.
Moore and Smith have found in the mouths and nasal cavities of healthy
animals, including cattle, bacteria belonging to this group; but these
organisms proved to be nonpathogenic. As is well known, however, many
pathogenic germs at times exist in a saprophytic state, and it is not hard
to conceive how a microbe may cease such existence and assume parasitic or
pathogenic properties when the surroundings are eminently favorable. This
may be a connecting link in the etiology of sporadic outbreaks of the
disease in which all other hypotheses as to its genesis seem untenable. The
disease seems to occur most frequently in swampy or mucky localities or in
pastures receiving the overflow from infected fields. It is said to occur
usually in the spring of the year, when the melting snows and rains bring
to the surface the subterranean waters from rich soils containing
nitrogenous materials in which the bacteria have been existing. In a great
many instances there does not seem to be any plausible explanation for an
outbreak of the disease and one can only surmise as to its origin.
_Symptoms._--Three forms of the disease are recognized, based upon the
distribution of the lesions--the superficial, or cutaneous, the pectoral,
or thoracic, and the intestinal form. The last is a usual accompaniment of
the other two and may be mild or severe. Naturally the symptoms vary
according to the violence of the attack and to the particular form of
disease with which the animal is affected. In the superficial, or
cutaneous, form the presence of a swollen tongue, throat, and dewlap, or
even of the lower portion of the legs, gives us a clew to the trouble. An
entire loss of appetite occurs, and in milk cows there is a diminution of
the milk secretion. The temperature may be only slightly elevated, but it
is usually very high. Salivation is set up by the inflammation of the mouth
and pharynx. Unsuccessful efforts at eating and swallowing are made. There
may be difficulty in breathing, depending on the amount of involvement of
the larynx, trachea, bronchi, or lungs. There may be a blood-stained
discharge from the nostrils, and the mucous membrane thereof will often
show punctiform hemorrhages. The pulmonary form shows the same symptoms as
croupous pneumonia, with a frequent suffocative cough and oppressed
breathing, or dyspnea. When the intestines are involved the patient strains
to defecate, and passes shreds of intestinal mucus along with blood-stained
feces. The urine also may be tinged with blood. Finally a severe diarrhea
takes place, the animal becomes correspondingly weak, and death takes place
in 24 to 36 hours. Cases may die in as short a period as six to eight
hours, while in the pectoral form of the disease the animal may linger six
or eight days. Cases have been reported which became chronic and in which
death did not take place for a month or more. In some of the cases running
an acute course, symptoms of toxemia are present; there is a lack of
sensation of the skin, staggering gait, trembling, eyes fixed, neck at
times bent to one side, and the eyes showing a wild expression. At times
the animals appear as if in pain and look around at the flanks. In the
pectoral form they may stand with the forelegs wide apart in evident effort
to breathe more freely. Sometimes there is a champing of the jaws and a
very free flow of glairy saliva dropping from the mouth.
The prognosis is decidedly unfavorable and 80 to 90 per cent of the cases
result fatally.
_Lesions._--The characteristic lesions of hemorrhagic septicemia consist of
hemorrhagic areas in the subcutaneous, subserous, and muscular tissues, the
lymph glands, and the viscera; in fact, they are distributed more or less
widely throughout the body and vary in size from a mere speck to the
diameter of a half dollar or even larger. The superficial form presents
itself first as a doughy tumefaction of the skin about the region of the
throat, neck, dewlap, or legs, which pits on pressure. This tumefaction
consists essentially of a cerogelatinous exudate into the subcutaneous and
intermuscular tissues.
Bloody extravasations may take place in subcutaneous tissues in various
places, but they are usually seen about the lower portion of the neck. The
mucous membranes and submucous tissues of the mouth, tongue, pharynx, and
larynx become involved in the process and are greatly thickened, inflamed,
and infiltrated with serum. The mucous membrane becomes reddish purple, and
that of the nostrils may in addition show hemorrhagic spots on its surface.
The lymphatic glands in this region are also swollen and infiltrated with
bloody serum. The salivary glands are pale and dry. The pectoral type,
though at times existing alone, may coexist with the cutaneous form. The
inflammatory edema of the mouth extends to the mucous membrane of the
trachea and bronchi, producing an extensive thickening and a yellowish
infiltration. The lung shows interstitial thickening from the outpouring of
serum into its meshes. It may become pneumonic.
The diaphragm, heart sac, and heart walls show numerous hemorrhagic points
and larger bloody extravasations. Sometimes there is a serous pleurisy,
with more or less fibrinous exudate. In the intestinal form the submucous
and subperitoneal tissues show alterations from a few hemorrhagic spots to
large bloody suffusions, or even gelatinous infiltrations. This latter is
seen about the region of the pancreas and in the folds of the mesentery.
There is a severe hemorrhagic inflammation of the intestines and a staining
of the intestinal contents with blood. The muscular system throughout shows
hemorrhagic areas. The abdominal viscera, liver, spleen, and kidneys often
present hemorrhagic lesions.
_Differential diagnosis._--Anthrax, which presents superficial swellings,
like hemorrhagic septicemia, may be distinguished from that affection on
post-mortem examination by the enlargement and engorgement of the spleen,
the contents of which are soft and tarry. The blood of anthrax animals is
very dark, and does not become light red on exposure to air, nor does it
coagulate, while in hemorrhagic septicemia the blood is normal in
appearance and coagulates. The detection of the anthrax bacillus in the
blood would be final.
In blackleg the animals affected are usually under 2 years of age. The
swellings are quite evident, and usually occur on the legs, above the knees
or hocks, and are distended with gas, which crackles, or crepitates, when
pressed upon. If one of these tumors is opened, a bloody serum will exude,
and the gas gives off the odor of rancid butter. The internal hemorrhages
are not general, although they may occur. A microscopic examination of the
juices from the tumefaction will show the blackleg bacillus.
In cerebrospinal meningitis the causative agent is unknown, but probably
exists in the feed. It may occur in any locality and at any season of the
year. There are no local swellings, and cattle are not frequently affected.
Cornstalk disease may be differentiated from this affection from the fact
that it always occurs after the cattle are turned into a cornstalk field,
by its sudden onset, the absence of any characteristic symptoms or
post-mortem lesions, and the failure to find the causative agent in the
blood.
In making a post-mortem examination of animals affected with hemorrhagic
septicemia, it would be well to examine the articular surfaces of the long
bones, as it has been reported that they are frequently ulcerated. This
should apply especially to those cases that have shown lameness.
_Treatment._--Treatment is absolutely useless, so far as we know at
present, and for all practical purposes prophylaxis alone should be relied
upon. The same sanitary precautions, such as isolation, disinfection, and
burial or burning of all dead carcasses, should be observed as for anthrax
and other highly infectious diseases. All the premises, barns, stalls,
litter, and stable utensils should be thoroughly disinfected. Separate the
apparently well animals from the sick by placing them in a separate lot.
Experiments by the Bureau of Animal Industry toward protective inoculation
of the exposed cattle on infected premises have been made and the results
have been so satisfactory that several commercial houses handling
biological products are manufacturing a vaccine for hemorrhagic septicemia
in accordance with the Government's experiments on this subject. The method
of preparing the vaccine is similar to that recommended by LigniËres. It
consists in growing the cultures of the organism of the disease at 42 to
43∞ C. and preparing from them growing at this temperature two different
strengths of vaccine. The weaker vaccine, which is used for the first
injection, is grown for five days at this temperature, whereas the stronger
vaccine, for the second injection, is grown for only two days. These
vaccines are used with an interval of 10 days between the injections, the
dose being 1 cubic centimeter at each injection. The effect of this vaccine
in abating outbreaks already in progress has been highly satisfactory and
it is plain that the general introduction of preventive vaccination for
hemorrhagic septicemia must be of material benefit to the cattle raisers in
the infected districts.
VESICULAR ERUPTION OF THE GENITAL ORGANS.
This contagious disease is called coital exanthema or vesicular exanthema,
and is more or less prevalent on the Continent. It has also been observed
in the breeding districts of the United States. It is the subject of
legislation in Germany, and governmental statistics are published annually
concerning its distribution in the Empire. According to the reports from
Hungary 492 head of cattle were attacked during 1898, 587 in 1899, and 207
in 1900.
A similar or perhaps identical disease of horses has the same distribution
and is transmissible from horses to cattle and vice versa.
The disease may be defined as a highly contagious eruption situated upon
the external genital organs of both sexes and accompanied with little or no
general disturbance of health. The contagion, the nature of which remains
still unknown, is transmitted mainly during copulation. The bull may have
the disease and convey it to all the cows with which he comes in contact,
or he may become infected by one cow, and, although not showing the
disease, he may, during copulation, transmit it for several days after to
all other cows. Simple contact between one cow and another may convey the
disease, or the sponges used in cleaning the diseased may carry the virus
to the healthy. It has also been conveyed to healthy cows by these animals
lying with their hind quarters against infected wooden troughs.
_Symptoms._--The period between the infection and the appearance of
symptoms is somewhat variable. It is usually given as three to six days. It
may be briefer or much longer. In cows the mucous membrane of the vagina
and the vulva become swollen, inflamed, very tender, and covered with
dark-red spots. The secretion is very abundant and consists at first
largely of serum and mucus resembling the white of an egg. Small vesicles
then appear, which rapidly burst and are converted into excoriations or
deeper ulcerations. The secretion becomes more purulent and is apt to dry
in crusts about the root of the tail. The eruption is accompanied with much
itching and difficulty in urinating. The walk may be stiff and awkward. In
bulls the eruption is situated on the prepuce and the end of the penis, and
consists of pimples, vesicles, and ulcers, as in cows. It is accompanied
with a little purulent discharge from the prepuce, itching, and difficulty
in urinating. In severe cases the inflammation and swelling may extend
backward to the scrotum and forward upon the abdomen.
The disease lasts from one to four weeks and always terminates in recovery.
The acute stage lasts only four or five days, while the complete healing of
the inflammation is slow. The eruption is usually accompanied with very
little general disturbance. If the pain and irritation are severe, there
may be some light loss of appetite and diminished milk secretion in cows.
The disease rarely causes abortion. Chronic catarrh of the vagina and
permanent sterility frequently follow as sequelÊ.
_Treatment_ need not be resorted to excepting in severe cases. The
secretion and exudation should be washed off and a mild antiseptic applied,
such as a 1 per cent solution of carbolic acid (1 ounce to 3 quarts of
water) or 2 per cent solution of cresol compound in water. Care must be
taken not to carry the disease from the sick to the well by sponges, etc.,
which have come in contact with the affected organs. These should be
destroyed. To prevent the spread of the disease the infected animals should
be kept isolated until they have recovered.
RABIES OF CATTLE.
Rabies is a disease preeminently affecting the canine race, although all
warm-blooded animals, including man, are susceptible to the malady, which
is always communicated through bites from a preceding case. It has required
many years of patient, scientific research to lead the ablest investigators
to a clear comprehension of the cause, nature, and characteristics of this
affection. It was known and described several centuries prior to the
beginning of the Christian era, and from the earliest dawn of history it
has been feared and dreaded. Its terrible manifestations have always been
surrounded with an atmosphere of awe and mystery, and it is not surprising
that myths, fallacies, and misconceptions in regard to it have been common
and widely accepted. As the investigations by which we have come to a
tolerably clear understanding of the facts concerning rabies have been
comparatively recent, and for the most part, have appeared in scientific
periodicals, fallacies in regard to the disease continue to have a strong
hold upon the public mind. For instance, it is still a widely prevalent
belief that if persons or animals are bitten by a dog they are liable to
become rabid if the dog should contract the disease at any future time.
There is no foundation for this impression, and it would be a great comfort
to many people who are now and then bitten by animals if the fallacy of
this idea were known. All experience, both scientific and practical, goes
to show that rabies is transmitted only by animals that are actually
diseased at the time the bite is inflicted. Rabies is an infectious disease
involving the nervous system and characterized by extreme excitability and
other nervous disorders and always terminating in death. The contagion of
this disease has never been isolated, but the fact that it is caused by a
specific organism principally found in the nervous system is indisputable.
For instance, if an emulsion of the brain of a rabid animal is filtered
through a germ-proof filter, the filtrate will be harmless. This fact
indicates that the infectious principle is not in solution, but is an
organism withheld from the filtrate by the filter. This contagion can be
propagated only in the body of an animal. It is transmitted naturally from
one animal to another solely by bites, and the old idea of spontaneous
appearance of the disease is absolutely fallacious. It may be produced
artificially by inoculating susceptible animals with an emulsion of the
brain or spinal cord, as well as the saliva, milk, and other secretions of
the affected animal. The blood, on the contrary, seems to be free from the
infectious principle. The saliva contains the virus, which, under natural
conditions, is introduced into or under the skin on the tooth of the rabid
animal. The disease is widespread, being found in many countries of Europe,
Asia, and Africa, and in certain sections of the United States.
Owing to the rigid quarantine regulations enforced against dogs imported
into Australia, that country remains absolutely free from the disease.
Following the canine race, cattle seem to be the most frequently affected,
probably because rabid dogs, next to their morbid desire to attack other
members of their own race, have a better opportunity to bite grazing cattle
than any other species of animal. The relative frequency of rabies in these
two species of animals is indicated by the carefully compiled statistics of
the German Empire, which shows that 904 dogs and 223 cows died of rabies in
1898, while in 1899 there were 911 cases in dogs and 171 in cattle. The
latter receive bites most frequently on the hind legs and in the hips and
about the lower jaw. These places are most accessible to dogs, owing to the
habit of cattle to drive their tormentors away by lowering their heads and
using their horns. Every animal bitten does not necessarily develop the
disease, but the per cent of fatalities has been variously estimated, and
averages from 25 to 30. This, however, depends on the location and size of
the wound as well as the amount of hemorrhage produced, and various other
conditions. In general, the nearer the bite is located to the central
nervous system and the deeper the wound inflicted, the greater the danger
of a fatal result. In cases in which the hemorrhage resulting from the bite
is profuse, there is a possibility that the virus will be washed out of the
wound and thus obviate the danger of subsequent appearance of the disease.
The virus after being deposited in the wound remains latent for an
extremely variable period of time, which also depends on the size and depth
of the wound as well as its location and the amount of the virulent saliva
introduced. Experiments have proved that the virus follows the course of
the nerves to the spinal cord and along the latter to the brain before the
symptoms appear. Gerlach, having collected the statistics from 133 cases,
has found this time, known as the period of incubation, to vary from 14 to
285 days. The great majority of cases, however, contract the disease in one
to three months after the bite has been inflicted.
_Symptoms._--As in dogs, both furious and dumb rabies are met with, the
former being more common in cattle. A sharp line of distinction, however,
can not be drawn between these two forms of the disease, as the furious
form usually merges into the dumb, from the paralysis which appears prior
to death. The typical cases of dumb rabies are those in which the paralysis
appears at the beginning of the attack and remains until death. The disease
first manifests itself by a loss of appetite and rumination, stopping of
the secretion of milk, great restlessness, anxiety, manifestation of fear,
and change in the disposition of the animal. This preliminary stage is
followed in a day or two by the stage of excitation, or madness, which is
indicated by increasing restlessness, loud roaring at times with a peculiar
change in the sound of the voice, violent butting with the horns and pawing
the ground with the feet, with an insane tendency to attack other animals,
although the desire to bite is not so marked in cattle as in the canine
race. A constant symptom is the increased secretion of saliva with a
consequent frothing at the mouth, or the secretion may hang from the lips
in long strings. Constipation is marked, and there is manifested a
continual, although unsuccessful, desire to defecate. Spasms of the muscles
in different parts of the body are also seen at intervals. About the fourth
day the animal usually becomes quieter and the walk is stiff, unsteady, and
swaying, showing that the final paralysis is coming on. This is called the
paralytic stage. The loss of flesh is extremely rapid, and even during the
short course of the disease the animal becomes exceedingly emaciated. The
temperature is never elevated, it usually remaining about normal or even
subnormal. Finally, there is complete paralysis of the hind quarters, the
animal being unable to rise, and but for irregular convulsive movements
lies in a comatose condition and dies usually from the fourth to the sixth
day after the appearance of the first symptom.
_Anatomy._--If animals which have succumbed to rabies are examined post
mortem, very slight evidence of disease will be found in any of the organs,
and, indeed, the absence of any specific lesions may be considered as
characteristic. The blood is dark and imperfectly coagulated. The throat is
frequently reddened, and there may be small spots of extravasated blood in
the intestines. The stomachs are usually empty. In the spleen there may be
hemorrhagic enlargements (infarcts). The cadavers rapidly undergo
decomposition.
_Differential diagnosis._--It is not an easy matter to decide definitely
that a given animal has rabies, since the symptoms given above belong in
part to a variety of other diseases, among which may be mentioned the
excitement seen in young animals following close confinement, certain
vegetable and mineral poisons, acute enteritis, and alterations of the
central nervous system in cattle, the most common of which is tuberculosis
of the brain and its covering membranes. The post-mortem lesions, however,
should assist in making a correct diagnosis. Tetanus may readily be
differentiated from rabies by the persistence of muscular cramps,
especially of the face and abdomen, which cause these muscles to become set
and as hard as wood. In tetanus there is also an absence of a depraved
appetite or of a willful propensity to hurt other animals or to damage the
surroundings. The cow remains quiet and the general muscular contraction
gives her a rigid appearance. There is an absence of paralysis which marks
the advanced stage of rabies. The form of dumb rabies in dogs is
characterized by the paralysis and pendency of the lower jaw, while in
tetanus the jaws are locked. This locking of the jaws in cattle renders the
animal incapable of bellowing, as in rabies. Finally, tetanus may be
distinguished from rabies by the fact that the central nervous system does
not contain the infectious principle, while in rabies the inoculation of
test rabbits with the brain or cord of a rabid animal will produce the
disease with characteristic symptoms after an interval of 15 to 20 days.
This period of incubation is much longer than in tetanus, since the
inoculation of rabbits with tetanus cultures invariably results in death
after a short period and usually within three days. The positive evidence
that a rabid dog has been near cattle would greatly assist in making a
decision in doubtful cases.
The disease in dogs is pretty well recognized by most people, but in case a
suspected dog is killed it is desirable to open the animal and examine the
contents of the stomach. While feed is absent, a variety of odd things may
be present which the abnormally changed appetite of the rabid dog has
induced it to swallow. Among such things may be straws, sticks, glass,
rags, earth, pieces of leather, and whatever the animal may have
encountered small enough to be swallowed. This miscellaneous collection in
the stomach of dogs, together with absence of feed, is regarded by
authorities as a very valuable sign, and in case of doubt may be made use
of by laymen. In important cases, however, the head of the dog, cow, or
other suspected animal should be removed and sent to the nearest biological
laboratory, where a positive diagnosis can be made within 36 hours by the
histological examination of the plexiform nerve ganglia, and within two or
three weeks by the intracerebral inoculation of rabbits with an emulsion of
the brain of the suspected animal.
_Treatment._--This is useless after the first appearance of symptoms. When,
however, a wound inflicted by a rabid animal can be discovered, it should
be immediately cauterized or even completely extirpated, care being taken
to cut entirely around the wound in the healthy tissues. For cauterizing
the wound, fuming nitric acid, the hot iron, and 10 per cent solution of
zinc chlorid are the most efficacious. To afford an absolute protection,
this should be done within a few moments after the bite has been inflicted,
although even as late as a few hours it has been known to thwart the
development of the disease.