Glanders appears in two primary forms—_acute_ and _chronic_, and each of
these is further divided according as the lesions are exclusively or
mainly seated in one part of the body or another. The generic term
_glanders_ is habitually used to designate that form in which the
lesions are situated in the nose, the nasal sinuses, and the
submaxillary lymphatic glands—_nasal glanders_. When the principle
lesions are situated in the lungs and lymph glands of the chest, the
case is one of _pulmonary glanders_. When the skin and subcutaneous
lymphatics are most prominently affected it is known as _farcy_ or
_cutaneous glanders_. When the skin and nose are simultaneously affected
the name _farcy glanders_ is sometimes applied. But as the bacillus may
enter by very varied channels the primary lesions may appear in still
other organs. Thus in stallions the first symptom is often a glanderous
orchitis. In other horses it may be a glanderous arthritis, and in still
others infected by ingestion it may be an abdominal infection.
_Symptoms of Nasal Glanders in Solipeds._ _Acute._ After an incubation
of three to five days the subject shows prostration, weariness,
stiffness, erection of the hair, and even tremor or shivering,
inappetence, thirst, hyperthermia, rapid pulse, weeping eyes, the
discharge becoming purulent, snuffling breathing, and a discharge from
the nose, at first serous, with a remarkable viscidity which tends to
glue together the long hairs or even the margins of the nostrils. This
discharge may be reddish, greenish, or brownish and may become
distinctly purulent and opaque. The _alæ nasi_ are swollen, hot and
painful, and the mucosa red, congested, thickened, with a blackish or
violet tint especially along the median part of the _septum nasi_. On
these, violet patches appear on the second or third day, pronounced
elevations of very varying size indicating the centres of active
hyperplasia. They are usually yellowish or grayish, surrounded by a deep
violet areola, and may become confluent forming patches. The centre of
each undergoes rapid degeneration, forming a rounded ulcer with salient
edges, a yellowish base, more or less pointed or streaked with red, and
a viscid seropurulent or bloody discharge which may concrete in crusts
or scale. The whole septum may become one continuous ulcer with
excavations of various depths surrounded by hyperplastic elevations, and
involving not only the mucosa, but even the cartilage and leading to
perforations.
From an early stage of the attack the submaxillary lymphatic glands and
the investing connective tissue become swollen, forming a mass of firm
bean- or pea-like nodules, with no excessive heat nor tenderness, and
with little disposition to suppurate and discharge. If this has lasted
for some time the glands often become more firmly attached to adjacent
parts (maxilla, tongue) by the contraction of the exudate.
The swelling of the alæ nasi also often extends to the skin of the face,
and firm, rounded cords formed by the swollen lymphatics stretch upward
toward the eye, or the submaxillary glands. Upon the turgid lymphatics
may appear more or less rounded nodules from the size of peas to hazel
nuts, which, unlike the submaxillary glands, tend to soften, burst and
discharge a viscid, glairy, sanious liquid.
At the same time the morbid process is liable to show itself in the
cutaneous lymphatics of one limb, usually a hind one, in the form of
firm cords, with degenerating or ulcerous nodules (farcy buds) and pasty
patches. Or the throat or lungs may become involved, with local
swellings, violent cough, dyspnœa and fever. The swellings of the
cutaneous lymphatics usually follow the course of the veins, in the hind
limbs the branches of the saphena, and extend from below upward, and the
first nodules may be on the fetlock or hock.
_Symptoms of Chronic Nasal Glanders in Solipeds._ The chronic form of
the disease follows an indolent course, and local symptoms are often so
slight or equivocal that the true nature of the malady is unsuspected.
If the patient is well fed and cared for and not overworked, the malady
may run a course of three, five or seven years, and the victim may pass
through many hands leaving infection in every stable it occupies.
Diagnostic symptoms, more or less clear, may be obtained from the
discharge; the lesions of the mucosa and the submaxillary glands.
The _nasal discharge_ may be bilateral, but if confined to one nostril
is strongly suggestive of glanders. It may be profuse or scanty,
continuous or intermittent, of a yellowish, purulent tint, or greenish,
or grayish and with a special tendency to viscidity. In some indolent
cases the nostrils may be clean but if there is any matting of the long
hairs, or adhesion of the alæ nasi, the case is specially suspicious. If
it is sanious, flocculent, or bloody it is all the more characteristic,
and suggests the supervention of an acute attack.
The _lesions of the pituitary membrane_ are varied. Hyperæmia of a
purple or violet color is common, especially along the septum, and the
mucosa is liable to be somewhat tumid or œdematous. Nodules the size of
a pin’s head, a pea or larger appear inside the inner ala, or on the
septum or turbinated bones, and at first red from extravasation and, as
it were vesicular, become grayish, whitish or yellow with points of red
and surrounded by a deeply congested areola. Larger nodules forming in
the submucosa approach the surface and stand out the size of the tip of
the finger and with the same general character as the smaller. Sooner or
later these degenerate and form ulcers which bear a resemblance to those
of acute glanders but are less angry, and when small and solitary may be
taken for simple erosions. In other cases they become thickened and
indurated with sharply defined projecting margins, and a yellowish base
with points or lines of red. The presence of red, black, green, or brown
crusts may also be noted.
Another lesion frequently observed in indolent cases is a cicatricial
white spot or patch in which the hyperplasia has become partially
developed into tissue and shows no tendency to ulcerate. The mucosa may
even be drawn or puckered around the cicatrix, making the illusion all
the more complete.
The _submaxillary swelling_ is even less sensitive than in acute
glanders and produces the same sensation as of an aggregation of small,
hard, pea-like, masses with no tendency to ulcerate.
_Symptoms of Cutaneous Glanders (Farcy) in Solipeds._ Acute cutaneous
glanders has been already referred to under nasal glanders. The chronic
type is often less characteristic, yet may be detected by careful
observation of the symptoms. The main symptom may be the swelling of a
joint with more or less engorgement of the limb from attendant
lymphangitis. There can usually be detected around the margins of such
swellings firm, tender cords representing the larger lymphatic vessels
and often branching in their course. In the absence of the engorgement,
or when it is slight, these _cords_ may be the main evidence of the
disorder, and in the hind limb usually follow the course of the flexor
tendons on the inner side of the digit, metacarpus and thigh. At
intervals along the line of the _cords_ appear nodular masses (farcy
buds) varying in size from a pea to a hen’s egg, and showing a great
disposition to soften and discharge a glairy, sanious or more or less
bloody liquid. The inner sides of the fetlock and tarsus are favorite
seats of these nodules but they may form at any point. On the trunk also
the corded lymphatics and nodules follow the lines of the veins and
lymphatics, and here there may be the complication of large
intermuscular abscesses often in connection with the groups of lymphatic
glands.
_Latent or occult glanders_ is often met with, the indolent, specific
lesions being confined to some internal organs, like the larynx, lungs
or womb, or to the testicles, the nasal diagnostic symptoms being
absent. A chronic cough, with a slight purulent discharge from the nose,
a chronic leucorrhœa, a swollen testicle, or simply a persistent low
condition or weakness without apparent cause, may be the only
indications, and special means of diagnosis are demanded.
_Special Means of Diagnosis._ In occult cases, the disease may be
identified by inoculation, or by the mallein test.
_Inoculation_ is best performed on a very susceptible animal. If the
suspected discharge from the nose, vagina, open sore or preferably from
a freshly incised nodule is inoculated subcutem in the flank of a male
Guinea pig, or better in the peritoneum, there develops a local ulcerous
sore and on the second or third day a violent orchitis in which pure
cultures of the bacillus can be obtained. The caseous and purulent
centres are found not only in the testicle but along the line of the
spermatic cord, affecting the tunica vaginalis and connective tissue.
Death usually follows in four to fifteen days. The cat and dog can also
be utilized, inoculation being made on the forehead. Old wornout, but
otherwise healthy asses, and even horses make very available subjects,
inoculation in the nose speedily developing acute glanders. In the
absence of a good subject the suspected animal is sometimes availed of,
scarifications being made in the nose and the morbid product rubbed in
freely. The rapid development of ulcerous wounds is characteristic. If,
however, the case is chronic, and if a fair measure of immunity has been
acquired this test may prove misleading.
_Test by Mallein._ Mallein is the sterilized and concentrated toxic
product obtained from a pure culture of bacillus mallei in a peptonized
glycerine bouillon. When injected hypodermically in a small
physiological dose this has no effect on a sound horse, but in one
affected with glanders it develops in several hours an extended swelling
in the seat of inoculation, hot, tense and painful, which continues to
enlarge for 24 to 36 hours and does not subside for 4 or 5 days. From
the margin of the swelling, swollen lymphatics may often be traced
running toward the adjacent lymphatic glands. There is also decided
dulness, prostration, inappetence, staring coat and tremors. The body
temperature rises 1.5° to 2.5° and upward from the eighth hour after
inoculation attaining its maximum from the tenth to the eighteenth hour
and subsiding slowly to the forty-eighth to the sixtieth.
Mallein must be used under precautions like tuberculin. It must be
obtained freshly prepared from a reputable maker. If preserved for
months its force may be largely lost. The animal to be tested should be
in his customary environment, and not just arrived from a railroad
journey nor other cause of excitement. He must not be fevered as any
rise of temperature is then equivocal, and a fall of temperature, which
sometimes occurs in the febrile system under mallein, is no sure
evidence of glanders. Reaction sometimes fails in advanced cases of
glanders, but in such a case other symptoms are usually diagnostic so
that mallein is superfluous and should not be misleading. The greatest
care should be taken to prevent infection from the syringe, nozzle,
skin, hands, etc., as other infections may give rise to local swelling
and hyperthermia (see tuberculin test). If a first test leaves the
matter in doubt, the animal should be secluded and tested again in a
month (some prefer 3 months).
_Pathological Anatomy._ The colonization of the bacillus mallei in a
tissue usually determines a concentration and multiplication of
leucocytes, so as to form rounded nests of small lymphoid cells in a
scanty fibrous network. These may be miliary or by aggregation they form
masses the size of a pea or larger, which bear a close resemblance to
the neoplasms of tuberculosis. As in tubercle the central cells of the
group, degenerate, forming a granular fatty debris, and constituting an
ulcer or abscess. In certain cases with a proliferation of fibrous
tissue a cicatricial material is developed. Another characteristic
lesion is the occurrence of hyperplasia in the walls of the lymph
vessels so as to constitute firm tender cords, and the infiltration of
the adjacent lymphatic plexus.
In the _nasal mucosa_ the bacilli form prolific colonies at different
points of the membrane and submucosa with the active production of
lymphoid cells, followed by granular fatty degeneration and ulceration.
Hence may be found different lesions representing the different stages.
First there may be miliary deposits with clear contents and standing out
like grains of sand. Then there are the larger pea-like nodules with
congested vessels and minute hæmorrhages, but made up largely of the
nests of lymphoid cells. These may bear on the surface a distinct blood
extravasation, or the epithelium may be raised from the corium layer by
a liquid exudation. The more advanced nodules show the centre light
colored, grayish or yellowish with a distinct granular degeneration of
the cells. Later still the degeneration involves the superficial layers
and epithelium and an open ulcer is formed with a strong tendency to
extend in depth and width. The formation and degeneration of numerous
foci of cell proliferation gives the ulcer a very uneven outline. The
continuous growth of fresh centres of proliferation may cause marked
elevations between the ulcers, constituting extended patches, or the
entire nasal mucosa may be thickened as the result of the morbid
deposit. The cicatrices resulting from the apparent healing of deep or
extensive ulcers or from a fibroid, transformation of the neoplasm
consist of condensed connective tissue with small scattered nests of
lymphoid cells and bacilli. In chronic cases the bacilli are very
scanty.
The mucosa of the _Eustachian pouches and tubes, the larynx, trachea and
bronchia_ often present lesions similar to those of the pituitary
membrane.
The _lungs_ are usually marked in chronic cases by circumscribed lobular
pneumonia, interlobular and peribronchial inflammations and miliary or
larger areas of degeneration resembling tubercles. These may begin as a
minute congestion and ecchymosis, which later shows in the centre a
translucent or gray mass of lymphoid cells, with a surrounding area of
congestion. Later still this central mass becomes yellowish and caseated
from granular and fatty degeneration and this gradually extends so as to
involve the whole area of the nodule. The peripheral portion may
condense into a fibroid envelope, but usually this is less smooth and
evenly rounded than in the case of an inspissated abscess or
bladder-worm. The bacilli are found in the affected tissue but not
always abundantly.
In _cutaneous glanders_ the lesions may begin in the papillary layer by
active congestion and infiltration and proliferation of lymphoid cells
which cause an eruption of rounded papules like small peas that
degenerate and soften and form superficial ulcers. When the derma is
mainly involved the inflamed area becomes the seat of larger hard
nodules which are at first deeply congested, with capillary thrombi,
minute extravasations and rapid cell proliferation; later on section
they show numerous caseated centres with a dense fibroid framework and
surrounded by an area of active congestion and capillary hæmorrhage;
later still the caseation and softening has caused rupture of the
investing epithelium and the discharge from the ulcerous cavity of a
yellowish, glairy, grumous liquid (open farcy buds). Sometimes the
nodule undergoes fibroid induration and fails to ulcerate, becoming the
counterpart of the cicatrices in the nose. When the infective
inflammation extends to the subcutaneous connective tissue, diffuse
engorgements and extensive swellings occur from the general infiltration
of the abundant lymph plexuses. Lymphoid cells accumulate in the
perivascular sheaths and lymph plexuses, the walls of the lymphatic
trunks running out of these swellings become swollen and indurated and
at intervals, mostly on the seat of the valves there is the
proliferation of small round cells to form farcy buds. In chronic cases
the fibroid thickening involves the skin, subcutaneous connective tissue
and walls of the lymph vessels binding the whole into one dense
resistant mass, more or less studded with corded lymphatics, firm
nodules, and ulcerous sores.
The _lymphatic glands_ in the line of circulation from the infected
centres are constantly involved. Hypertrophy, congestion, serous
infiltration, and rapid cell proliferation are present and a section
will usually show caseated or caseopurulent centres confined by the
outer dense fibrous envelope. Exceptionally, these necrosed contents
will escape through an ulcerous opening, forming a deep cavity which is
slow and difficult to heal. In the vicinity of these glands and in the
loose intermuscular connective tissue abscesses of the size of an egg or
an orange or larger are sometimes met with.
Nodules and ulcers are found on the pharyngeal and intestinal mucosa,
similar to those of the larynx.
The spleen, and less frequently the liver, may be the seat of caseating
nodules exactly comparable to those of the lungs. Glanders of the kidney
is rare.
Nodules have been seen on the ventricular endocardium and one case of
nodules of the choroid plexus (Boschetti).
In stallions, glanderous, caseating foci in the _testicle_ and dropsy of
the scrotum are common, while mares may have similar formations in the
mammary glands or ulcers of the vaginal or uterine mucosa.
Infiltrations of the joints and other synovial cavities are not uncommon
and glanderous infiltration of the bones with caries is also found. In
chronic cases, fragility of the bone is marked, and the blood contains
an excess of leucocytes. These may be traced to disease of the bone
marrow, as well as of the spleen and lymphatic system.