neighboring lymphatics; and in the intermaxillary space, deep inside of
the jaws, we find an enlargement of the glands, which for the first few
days may seem soft and edematous, but which rapidly becomes confined to
the glands, these being from the size of an almond to that of a small
bunch of berries, exceedingly hard and nodulated. This enlargement of
the glands is found high on the inside of the jaws, firmly adherent to
the base of the tongue. It is not to be confounded with the puffy,
edematous swelling, which is not separated from the skin and
subcutaneous connective tissues found in strangles, in laryngitis, and
in other simple inflammatory troubles.
These glands bear a great resemblance to the indurated glands which we
find in connection with the collection of pus in the sinuses; but in the
latter disease the glands have not the extreme nodulated feel which they
have in glanders. With the glands we find indurated cords, feeling like
balls of tangled wire or twine, fastening the glands together.
The essential symptoms of glanders are the nodule, the chancre, the
glands, and the discharge. With the development of the nodules in the
respiratory tract, according to their number and the amount of eruption
which they cause, we may find a cough which resembles that of a coryza,
a laryngitis, a bronchitis, or a broncho-pneumonia, according to the
location of the lesions. In chronic glanders we find the same accessory
symptoms that occur in chronic farcy, the hemorrhage of the nose, the
swelling of the legs, the chronic cough, and, in the entire horse, the
swelling of the testicles.
On healing, the chancres on the mucous membranes leave small, whitish,
star-shaped scars, hard and indurated to the touch, and which remain for
almost an indefinite time. The chancres heal and the other local
symptoms disappear, with the exception of the enlargement of the glands,
and we find these so diminished in size that they are scarcely
perceptible on examination. During the subacute attacks, with a minimum
quantity of local troubles, in chronic glanders and in chronic farcy the
animal rarely shows any degree of fever, but does have a generally
depraved appearance; it loses flesh and becomes hidebound; the skin
becomes dry and the hairs stand on end. There is a cachexia, however,
which resembles greatly that of any chronic, organic trouble, but is not
diagnostic, although it has in it certain appearances and conditions
which often render the animal suspicious to the eye of the expert
veterinarian, while, without the presence of local lesions he would be
unable to state on what he has based his opinion.
ACUTE GLANDERS.
_Symptoms._--In the acute form of glanders we find the symptoms which we
have just studied in chronic farcy and in chronic glanders in a more
acute and aggravated form. There is a rapid outbreak of nodules in the
respiratory tract which rapidly degenerate into chancres and pour out a
considerable discharge from the nostrils. There is a cough of more or
less severity according to the amount and site of the local eruption.
Over the surface of the body swellings occur which are rapidly followed
by farcy buttons, which break into ulcers; we find the indurated cords
and enlargement of the lymphatics.
Bleeding from the nose, sudden swelling of one of the hind legs, and the
swelling of the testicles are liable to precede an acute eruption of
glanders. As the symptoms become more marked the animal has difficulty
of respiration, the flanks heave, the respiration becomes rapid, the
pulse becomes quickened, and the temperature becomes elevated to 103 deg.,
104 deg., or 105 deg. F.
With the other symptoms of an acute fever the general appearance and
station of the animal is that of one suffering from an acute pneumonia,
but upon examination, while we may find sibilant and mucous rales over
the side of the chest, and may possibly hear tubular murmurs at the base
of the neck over the trachea, we fail to find the tubular murmur or the
large area of dullness on percussion over the sides of the chest which
belongs to simple pneumonia.
_Diagnosis._--When there is doubt as to the diagnosis, the mallein test,
the inoculation test, or the complement-fixation test may be employed.
The mallein test is made by injecting mallein (a sterilized extract from
a culture of glanders bacilli) beneath the skin. If the horse has
glanders there results a febrile reaction and a swelling at the point of
injection. If the horse does not have glanders the mallein has no effect
or, at most, it produces a slight swelling only at the point of
injection. The inoculation test consists in the inoculation of a
susceptible animal (usually a guinea pig) with some of the suspected
discharge from the nose or a farcy ulcer. If the material is properly
used, and if it contains bacilli of glanders, the experimental animal
will develop the disease.
The eye test is now universally accepted as a very satisfactory means of
diagnosing glanders. This consists in dropping into an eye of a
suspected animal a specially prepared solution of mallein, as a result
of which in an infected animal the inflammation develops in the eye,
resulting in a discharge which varies in intensity from a mucopurulent
character to a thick, sticky pus. The eyelids may also swell and many
times become glued together. The reaction usually appears in from 8 to
20 hours after the introduction of the mallein.
Neither of these tests should be put into use except by a competent
veterinarian. The complement-fixation test is a highly specialized
laboratory test and can be carried out only by one versed in laboratory
technique. (See Bureau of Animal Industry Bulletin 136.)
The post-mortem examination of the lungs shows that the pneumonia of
glanders is a lobular, V-shaped pneumonia scattered throughout the lungs
and caused by the specific inflammatory process taking place at the
divergence of the smaller air tubes of the lungs. In some cases of acute
glanders the formation of nodules may so irritate the mucous membrane of
the respiratory tract and cause such a profuse discharge of mucopurulent
or purulent matter that the specific character of the original discharge
is entirely masked. In this case, too, for a few days the submaxillary
space may so swell as to resemble the edematous, inflamed glands of
strangles, equine variola, or laryngitis. This condition is especially
liable to be marked in an acute outbreak of glanders in a drove of
mules.
Cases of chronic farcy and glanders, if not destroyed, may live in a
depraved condition until the animal dies from general emaciation and
anemia, but in the majority of cases, from some sudden exposure to cold,
it develops an acute pneumonia or other simple inflammatory trouble
which starts the latent disease and the animal has acute glanders.
In the ass, mule, and plethoric horses acute glanders usually terminates
by lobular pneumonia. In other cases the general symptoms may subside.
The symptoms of pneumonia gradually disappear, the temperature lowers,
the pulse becomes slower, the ulcers heal, leaving small, indurated
cicatrices, and the animal may return to apparent health, or may at
least be able to do a small amount of work with but a few symptoms of
the disease remaining in a chronic form. During the attack of acute
glanders the inflammation of the nasal cavities frequently spreads into
the sinuses or air cells, which are found in the forehead and in front
of the eyes on either side of the face, and causes abscesses of these
cavities, which may remain as the only visible symptom of the disease.
An animal which has recovered from a case of acute glanders, like the
animals which are affected by chronic glanders and chronic farcy, is
liable to be affected with emphysema of the lungs (heaves), and to have
a chronic cough. In this condition it may continue for a long period,
serving as a dangerous source of contagion, the more so because the
slight quantity of discharge does not serve as a warning to the owner or
driver as profuse discharge does in the more acute cases.
At the post-mortem examination of an animal which has been destroyed or
has died of glanders we find evidences of the various lesions which we
have studied in the symptoms. In addition to this, we find nodules
similar to those which we have seen on the exterior throughout the
various organs of the body. Nodules may be found in the liver, in the
spleen, and in the kidneys. We may find inflammation of the periosteum
of the bones, and we have excessive alterations in the marrow in the
interior of the bones themselves. Both these conditions during the life
of the animal may have been the cause of the lamenesses which were
difficult to diagnose.
In one case which came under the observation of the writer, a lame horse
was destroyed and found to have a large abscess of the bone of the arm,
with old nodules of the lungs. When an animal has died immediately after
an attack of a primary, acute case of glanders, we find small V-shaped
spots of acute pneumonia in the lungs. If the animal has made an
apparent recovery from acute glanders, and in cases of chronic farcy
and chronic glanders, no matter how few the external and visible
symptoms may have been, there is a deposit of nodules--small, hard,
indurated nodes--of new connective tissue to be found in the lungs. When
these have existed for some time we may find a deposit of lime salts in
them. These indurated nodules retain the virus and their power to give
out contagion for almost an indefinite time, and predispose to the
causes which we have studied as the common factors in developing a
chronic case into an acute case; that is, an inflammatory process wakens
their vitality and produces a reinfection of the entire animal. The
blood of an animal suffering from chronic glanders and farcy is not
virulent and is unaltered, but during the attack of acute glanders,
while the animal has fever, the blood becomes virulent and remains so
for a few days.
_Treatment._--Almost the entire list of drugs in the pharmacopoeia has
been tested in the treatment of glanders. Good hygienic surroundings,
good feed, with alteratives and tonics, frequently ameliorate the
symptoms, and often do so to such an extent that the animal would pass
the examination of any expert as a perfectly sound animal. While in this
case the number of nodules of the lungs, which are invariably there, may
be so few as not to cause sufficient disturbance in the respiration as
to attract the attention of the examiner, yet they exist, and will
remain there almost indefinitely, with the constant possibility of a
return of acute symptoms.
It is probable that some horses may recover from glanders if the
infection is slight, but it will not do to depend upon this except under
the most stringent veterinary supervision. With good care, good feed,
good surroundings and little work, an animal affected with glanders may
live for months or even years in a state of apparently perfect health,
but with the first deprivation of feed, with a few days of severe hard
work, with exposure to cold or with the attack of a simple fever or
inflammatory trouble from other causes, the latent seeds of the disease
break out and develop the trouble again in an acute form.
In several celebrated cases horses which have been affected with
glanders have been known to work for years and die from other causes
without ever having had the return of symptoms; but allowing that these
cases may occur, they are so few and far between, and the danger of
infection of glanders to other horses and to the stable attendants is so
great, that no animal which has once been affected with the disease
should be allowed to live unless repeated mallein tests have shown him
to have become free from taint of glanders.
In all civilized countries, with the exception of some of the States in
the United States, the laws are most stringent regarding the prompt
declaration on the part of the owner and attending veterinarian at the
first suspicion of a case of glanders, and they allow indemnity for the
animal. When this is done, in all cases the animal is destroyed and the
articles with which it has been in contact are thoroughly disinfected.
When the attendants have attempted to hide the presence of the disease
in a community, punishment is meted out to the owner, attending
veterinarian, or other responsible parties. Several States have passed
excellent laws in regard to glanders, but these laws are not always
carried out with the rigidity with which they should be.
SPOROTRICHOSIS (MYCOTIC LYMPHANGITIS).
By JOHN R. MOHLER, V. M. D., _Assistant Chief, Bureau of Animal
Industry_.
This disease has previously been known in this country as epizootic
lymphangitis, or pseudo-farcy. It is a chronic, contagious disease,
particularly of equines, caused by a specific organism, the
_Sporotrichum schenckii_, and characterized by a suppurative
inflammation of the subcutaneous lymph vessels and the neighboring lymph
glands. Owing to the fact that this affection does not spread as an
epizootic and that its causal factor is a fungus, the name
sporotrichosis has been suggested.
The disease in man was first described by Schenck and by Beurmann and
Gougerot. Carougeau observed its occurrence among horses and mules in
Madagascar, while in the United States it was first observed by Pearson
in Pennsylvania in 1907, although it is probable that it had existed for
many years in various parts of this country. Page and Frothingham were
first to recognize its mycotic nature in the United States. More
recently Meyer has also made valuable contributions with regard to the
existence of this affection. Its presence has been definitely
established in Ohio, Iowa, California, and North Dakota, and there is a
probability of its existence in Indiana and several Western States.
_Bacteriology._--The sporotrichum is 2 microns thick, cylindrical and
segmented, having more or less branching threads, which bear spores at
the end. In the pus they occur as slightly ovoid bodies 3 to 5 microns
long, which are somewhat pointed toward the poles, have a sharp double
contour, and only on artificial cultivation at a temperature of over 18 deg.
do they develop into the characteristic spore-carrying threads.
The period of incubation varies greatly, extending from three days to
four months, or even longer. In artificial inoculations with pus through
wounds in the skin, inflammation and swelling of the lymph vessels may
be noticed in ten to sixty days; these vessels show in their course a
development of hard nodules, from which abscesses form.
The natural infection without doubt is caused through superficial
wounds, such as galls, barbed-wire cuts, or through various stable
utensils, harness, bandages, insects, etc. Solipeds are mostly
susceptible, but cattle may also be infected.
_Symptoms._--The inflammation of the lymph vessels is usually first
observed on the extremities, especially on one or both hind legs; it may
also appear on the forelegs, shoulder, or neck, and more rarely on the
rump, udder, and scrotum. The lesions, as a rule, develop in the tissue
adjacent to the place of inoculation. In the early stages of the disease
the lymph vessels appear very hard and thickened, and along their course
hard nodules develop, ranging in size from a pea to a hen's egg. Later
these nodules soften, burst spontaneously, and discharge a thick,
yellowish pus. The surface of the resulting ulcers or abscess cavities
soon fills up with exuberant granulations which protrude beyond the
surface of the skin, giving it a fungoid appearance. The affected
extremities are considerably enlarged, similar to cases of simple
lymphangitis. In rare cases the mucous membrane of the nostrils may also
become affected, showing yellowish flat elevations and ulcerations, and
these may extend by metastasis to internal organs. In cases in which the
mucous membrane is affected, the submaxillary lymph gland may also
become enlarged and suppurate.
The constitutional symptoms accompanying this disease are not very
marked and may be altogether absent. There is usually only a very slight
fever, which seldom runs over 102 deg. F. The appetite is not impaired
except in the advanced cases.
_Lesions._--The anatomical changes are most marked in the skin and the
subcutaneous tissues. They may become 2 to 3 inches thick and indurated
as the result of fibrous-tissue formation, owing to the inflammation
present. On the baconlike cut surface suppurative areas and granulating
sores may be noticed of various sizes, also enlarged lymph vessels
filled with clotted lymph mixed with pus. The neighboring lymph glands
are usually enlarged and frequently contain suppurating foci. Rarely the
internal organs may show metastatic abscesses.
_Diagnosis._--The diagnosis is based on the characteristic appearance of
the ulcerations, which show exuberant granulation of a bright red color,
inverted edges, and a thick, creamy, glutinous discharge. These
manifestations differentiate the disease from glanders, in which the
ulcers are craterlike, do contain exuberant granulations, and the
discharge is of a viscous, oily character. The submaxillary and other
nodes as well as the corded lymphatics in glanders are more firmly
attached to the adjacent tissues, and are therefore less movable. In
some chronic cases of sporotrichosis, however, the lesions may closely
resemble those of farcy, and in these cases the microscopical
examination of the pus will disclose the nature of the affection. In the
pus the causative organism can be easily seen in the unstained specimen,
and is recognized by its size, shape, and highly refractory double
outline. Furthermore, the injection of mallein in cases of
sporotrichosis will be attended with negative results.
_Treatment._--At the onset of the disease treatment consists in entire
extirpation of the nodules, in case the lesions are localized. In cases
in which the nodules have formed abscesses, their opening is
recommended, followed by the application of the actual cautery or a 1 to
250 solution of bichlorid of mercury. It must be borne in mind that the
organism is quite resistant to antiseptics, and the best results will be
obtained from the application of a solution of a strong antiseptic
following the opening of the lesions. Internally, potassium iodid is
recommended in 2-dram doses, dissolved in drinking water, twice a day.
In the most favorable cases recovery results in from five to seven
weeks; as a rule, however, it requires several months.
In order to prevent the spreading of the disease the affected animals
should be isolated, the products of the disease should be destroyed, and
the stable should be disinfected with very strong liquid disinfectants
in consideration of the resistance of the causative organism.
RABIES, HYDROPHOBIA, OR MADNESS.
Rabies is a contagious disease, which is usually transmitted by a bite
and by the introduction of a virus contained in the saliva of an
affected animal. It may, however, be transmitted in other ways. It is
characterized by symptoms of aberration of the nervous system and
invariably terminates fatally. It is accompanied with lesions,
inflammation, and degeneration in the central nervous system. It is a
disease that is most common in the dog, but is transmitted to the horse,
either from dogs or from any other animal affected with it. (See also
remarks on page 244.) As a disease of the horse it is invariably the
result of the bite of a rabid animal, usually a dog.
Perhaps no disease in medicine has been the object of more controversy
than rabies. Certain medical men of prominence have even doubted its
existence, and many others have claimed for it a spontaneous origin. The
experience of ages, however, has shown that contagion can be proved in
the great majority of cases, and, by analogy with other contagious
diseases, we may only believe that the development of one case requires
the preexistence of a case from which the virus has been transmitted.
Pasteur has further added to our knowledge of the disease by showing
that a virus capable of cultivation exists in the nervous system,
especially in the lower part of the brain (medulla oblongata) and in the
anterior part of the spinal column. He has further shown that that
portion of the nervous system which contains the virus, the exact nature
of which has not yet been demonstrated, will retain it for a very long
time if kept at a very low temperature or if left surrounded by
carbolic acid; but if the nerve matter, which is virulent at first, is
exposed to the air and is kept from putrefaction by substances which
will absorb the surrounding moisture, it will gradually lose its
virulence and become inoffensive in about fifteen days. He has also
further shown that the action of a weak virus on an animal will prevent
the development of a stronger virus, and from this he has formulated his
method of prophylactic treatment. This treatment consists in the
successive inoculation of portions of the nerve matter containing the
virus from a rabid animal which has been exposed to the atmosphere for
thirteen days, ten days, seven days, and four days, until the virulent
matter which will produce rabies in any unprotected animal can be
inoculated with impunity. A curious result of the experiments of Pasteur
is that an animal which has first been inoculated with a virus of full
strength can be protected by subsequent inoculations of attenuated virus
repeated in doses of increasing strength.
Innumerable attempts have been made to discover the causative agent, and
investigators have announced the finding of many of the lower forms of
animal and vegetable life as the pathogenic factor. Among the recently
described causes, certain protozoanlike bodies found in the ganglionic
cells in 1903 by Negri, and termed Negri bodies, are of a very
suggestive nature. Negri claims that these bodies are not only specific
for rabies, but that they are protozoa and the cause of the disease. His
work has been corroborated by investigators in all parts of the
scientific world. An examination of the vitality of these bodies will
show a striking resemblance to the vitality of an emulsion of the
virulent tissue. Thus, they have been found to be quite resistant to
external agencies, such as putrefaction, drying, etc., and are about the
last portion of the nerve cell to survive the advance of decomposition.
They are also found in more than 96 per cent of the cases of rabies
examined, but have not been proved to exist in other diseases.
Valenti states, as his strongest evidence of the protozoan nature of the
bodies, that the virus of rabies is neutralized in test tubes by quinin,
while no other alkaloid has this property. As a result of the work
performed in the New York City Board of Health laboratory, Park claims
that Negri bodies are found in animals before the beginning of visible
symptoms, and evidence is given that they may be found early enough to
account for the infectiousness of the central nervous system. These
bodies are now almost universally considered as diagnostic of rabies,
and in the pathological laboratory of the Bureau of Animal Industry
their detection in the nerve cells of the brain suffices for a diagnosis
of rabies without animal inoculations. In case these granular bodies are
not found in a suspected animal, the plexiform ganglion is next
examined, and should negative results still be obtained, the inoculation
of rabbits is then made as a last resort. It is indeed rare that
positive results are obtained from the latter method after the first two
methods have been negative, but it has occurred occasionally in cases in
which the animal had been killed in the early stages of the disease.