The characteristic lesion in tuberculosis is the tubercle, taking its
name from the small rounded nodule which, at first virtually invisible,
encreases often to the size of a millet seed, or a pinhead or even
larger, and which by confluence with others, forms conglomerate masses
of all sizes to which the term tubercle is still applied. Where the
bacillus tuberculosis is implanted, the fixed tissue cells are
stimulated to an undue proliferation, and a diapedesis of leucocytes
takes place from the neighboring capillary blood vessels, the whole
eventuating in the formation of a rounded cluster or nest of epithelioid
and giant and later small rounded lymphoid cells in a fine fibrous
stroma. Baumgarten and his followers claim that the larger epithelioid
and giant cells result from the karyokinesis and proliferation of the
fixed tissue cells, epithelial and endothelial cells, and that the
lymphoid cells which later (often after the eighth day in experimental
cases) invade the lesions, are alone the product of the migrating
leucocytes. Metchnikoff, Yersin and others contend, on the other hand,
that epithelioid and giant cells are directly derived from the
leucocytes and endothelial cells and like these are possessed of
actively phagocytic qualities. As the final outcome before caseous
degeneration, is the great predominance of the small lymphoid cell, it
may well be questioned whether this is not the result of active encrease
in both kinds of cells, as appears to happen in many other
inflammations. For our present purpose it is well to note the early
characters: _Centrally_ often a large (giant) cell with a number of
peripheral nuclei and at times, branching processes; around this as a
_second zone_ epithelioid cells of large size, with round or oval
nuclei, and sometimes giant cells; outside this a _third zone_ of small
rounded lymphoid cells with large nuclei. There is a delicate fibrous
network between the cells, but no indication of capillary blood vessels,
the absence of which may partly explain the constant tendency to
degeneration, necrosis, and caseation. The tissue around the miliary
tubercle is red and congested.
_Caseation._ A striking characteristic of tubercle is the occurrence of
coagulation necrosis, beginning in the centre of the specific nodule as
a whitish or pale softening and degeneration of the cell elements and
gradually extending toward the circumference. The cells, and even the
proximate tissue elements, die and disintegrate passing into a
structureless, granular or hyaline debris, which has been named from its
supposed resemblance to old, ripe, soft cheese. Baumgarten has observed
that the small lymphoid cells are the first to degenerate, followed by
the epithelioid and giant ones.
While the formation of tubercle is at first a productive inflammation of
which the cell clusters and nodules are the result, yet the tendency to
necrosis, and caseation is so great that it must be looked upon as one
of its most prominent features, and is rarely absent, whether the lesion
exists in the connective tissue of the lungs, liver or other organ, in
the lymph glands, in the respiratory or intestinal mucosa or submucosa,
in the osseous cancelli, brain or skin. It is, therefore, largely
pathognomonic, yet it is not peculiar to tubercle, being common in
glanders, and other infective inflammations. Its presence should always
lead to a search for the primary tubercle nodule, with its nonvascular
cluster of lymphoid and giant cells and above all for the specific
bacillus resistant to staining.
The tendency to extensive degeneration and caseation is especially
marked in swine, in which the resulting debris is often so liquid that
the tubercles bear a strong resemblance to abscesses.
_Calcification._ The deposition of lime salts (mainly phosphates) in the
tubercle is a common feature of advanced cases in man and pig, but
especially in cattle. It is unknown in rabbits and Guinea pigs. The
tubercle assumes a hard cretaceous aspect and feeling, grates under the
knife and crepitates when pressed. This is always an evidence of
chronicity, but it has been observed in swine in 3½ months.
_Fibroid Degeneration. Fibrosis._ In this case a productive fibroid
inflammation takes place in the tissue of the tubercle, and it is
resolved more or less extensively into a hard, white, resistant body.
This is the pearly mass which has given rise to the name of the _pearl
disease_ (perl-zucht) in Germany. It may be fibrous throughout, but
usually a number of the nodules show a caseated centre while the
external zone, that nearest to healthy tissue, has alone taken on the
conservative fibroid development. Like cretifaction, fibrosis is an
indication of chronicity in the lesion. It is often seen in man, but
still more so in cattle, in which it affects particularly the abdominal
cavity, but also to a lesser extent the chest and other parts. It is
remarkable for the paucity of bacilli to be found in its substance,
often requiring many sections and infinite patience to reveal the
presence of the microbe. This comparative lack of actively multiplying
bacilli is doubtless one factor, operating in the direction of
conservative processes, chronicity and even partial recovery. In
experimental tuberculosis the extent and rapidity of development of
tubercle, as also of the degeneration are found to be closely allied to
the number of bacilli introduced.
_Cattle: Pulmonary Tuberculosis._ One of the most frequent seats of
tuberculosis, the lung, may in acute cases show a diffuse miliary
tuberculosis, a considerable part of a lobe or of several lobes being
congested, infiltrated, and filled with small individual tubercles,
grayish or transparent in the midst of the general redness. A second
form, often of old standing, is in the shape of hard masses, often
circumscribed or isolated, and easily felt when the soft lung tissue is
manipulated. They are respectively formed by the local aggregation, and
confluence of the small miliary nodules and may vary in size from a pea
to a mass of ten or twelve inches in diameter. On section the miliary
tubercle may not yet show central caseation, but the larger ones do so
as a rule. The caseated nucleus may be soft, cheesy and somewhat
homogeneous; it may be dry, granular and yellow, resembling damp farina
of maize; it may be calcified in its outer portion and invested by a
firm fibrous envelope. The tubercle may be the seat of general fibroid
degeneration, constituting the pearl nodules (perl-knoten) dense as
cartilage and either with or without a soft caseated centre; it may show
an agglomeration of nodules in all stages from the early congested
nodule to advanced caseation or cretefaction, the whole embedded in a
solid congested and infiltrated tissue, largely fibroid. There may be
extensive abscesses, the seats of complex infections, having thick
uneven walls, often showing _grape like_ tuberculous outgrowths, and
containing thick, caseopurulent, viscous, granular, yellowish or
greenish and comparatively odorless contents; in other cases the
abscesses have burst into the bronchia, leaving _vomicæ_ and with the
new resultant infections the contents have acquired an offensive putrid
odor; finally, there may be extensive inflammatory infiltrations,
affecting lobules or lobes, and interspersed with tubercles in the form
of the early grayish or transparent nodule, or even more advanced
caseous or cretaceous centres. These latter serve to distinguish the
condition from broncho-pneumonia, the grayish centres of which might
suggest miliary tubercle. The broncho-pneumonia, however, has the
whitish centres confined to the bronchioles and their terminal air sacs,
and represent their thickened walls and muco-fibrinous contents; they do
not show the same tendency to caseation, nor necrosis of the tissue, nor
to caseation of the dependent lymph glands, and, above all, they do not
contain the bacillus tuberculosis.
A noticeable feature in the tuberculous lung is the great frequency of
tubercles of all different ages from the initial transparent nodule to
the caseated or calcified mass side by side. A tuberculous bronchitis is
a familiar accompaniment, with lines of miliary tubercles, ulcers and a
flocculent (sometimes gritty) muco-purulent discharge, containing
elements of the necrotic tissue and bacilli. Emphysema and interlobular
œdema are also met with.
The _Pleuræ_ often suffer by continuity of tissue from the diseased
lung, but they may be affected primarily through infection of the
circulating blood. The earliest pleural lesions may be congestion,
exudation and the formation of false membranes in fringes, but soon
these become the seats of minute nodules or forming tubercles which
steadily encrease to form pale red cauliflower-like growths—which have
been spoken of as _grapes_, from their supposed resemblance to bunches
of that fruit. Extensive areas of the mediastinal, costal or pulmonic
pleuræ are often completely covered by these productions. Dense, and
thick adhesions sometimes form, holding in their substance
characteristic tubercles.
The _bronchial and mediastinal lymph glands_ receiving as they do the
afferent trunks from the lungs and the great lymph sac of the pleura,
offer in their sluggish currents the most favorable culture vessels, and
almost always become affected in consequence. Not unfrequently they are
found to be tuberculous when the tissues which they drain appear to be
sound, and we must therefore, conclude that the primary slight lesions
in the latter have recovered, or that the bacilli have passed through
the tissues and lymph channels without establishing any centre of
disease. The glandular lesions are primarily congestion and redness,
with more or less infiltration and swelling, followed by a nodular
induration, with enlargement or exceptionally shrinking. When bisected
they may show all stages of the tubercle from the miliary granule to the
caseous, dry, yellow, granular or cretaceous necrosis. By aggregation
these often grow to a large size, a long diameter of 6 to 12 inches
being not uncommon.
_Pericardial and Cardiac Lesions._ The pericardium may be implicated
from the pleuræ or independently, and though tuberculosis of the heart
is rare, it may be the seat of primary tuberculosis or of extension from
the pericardium or endocardium. In the N. Y. State Veterinary College
Museum is a cow’s heart, greatly enlarged, and completely invested and
invaded by tubercle several inches thick.
_Tuberculosis of the Mouth and Throat._ Tubercles sometimes form in the
_tongue_ causing nodular swelling, with a caseated centre. Much more
frequently they attack the _pharynx_ or _larynx_ with the formation of
nodular necrotic swellings, followed by ulcers and the implication of
the adjacent lymph glands. The glands are liable to be invaded through
the tonsillar and other follicles of the faucial and pharyngeal regions,
which like the solitary and agminated glands of the intestines form
excellent culture vessels. The glands most frequently attacked are the
_retro-pharyngeal_, but the _lateral pharyngeal_, the _intra-parotidean_
and _submaxillary_ lymph glands occasionally suffer. They often become
indurated, yet the formation of abscess-like sacs is not uncommon
especially in the retro-pharyngeal.
_Gastro-Intestinal_, _Peritoneal_ and _Mesenteric Tubercles_. Tubercles
of the interior of the stomachs are rare, though they are frequent on
the peritoneal surface of the first three stomachs, as rounded,
subserous nodules varying in size from a pea upward. The _mucosa of the
small and large intestines_ may suffer, by preference in the seats of
the solitary or agminated glands, and the resulting ulcers may extend in
the lines of the lymph vessels from the convex to the attached border of
the gut. The small greenish caseated and calcified nodules on the
intestines, which are so often mistaken for tubercles, are the
degenerated cysts of the œsophagastoma. Tuberculosis of the mesenteric
lymph glands is much more common, the successive stages being
essentially like that seen in the bronchial glands. Beside these the
surface of the mesentery, omentum and abdominal parietes often becomes
the seat of congestion, exudation and cauliflower-like neoplasms or
grapes, as already stated of the pleuræ. In a certain number caseation
or cretefaction may be detected.
_Liver Tuberculosis._ The liver is greatly exposed to tuberculosis as
the single destination of all the blood from the gastro-intestinal
tract. Tubercles also form on its surface by direct infection from the
peritoneum. The hepatic tubercles are often very large and numerous,
adding greatly to the bulk and weight of the viscus. There is usually
coincident tuberculosis of the lymph glands of the porta.
_Tubercle of the Spleen._ This is also a favorite seat of the morbid
process, exposed as it is to the reflux of infected blood in the portal
vein, and to access of the bacillus from the peritoneum and omental
lymphatics.
The _pancreas_ is less exposed to the channels of the circulation and is
less frequently affected.
_Genito-Urinary Tubercles._ The _kidneys_ are always liable to suffer in
generalized tuberculosis, in accordance with their function of
elimination and the great quantity of blood that passes through them.
The tubercles may be numerous, encroaching upon and destroying the
glandular tissue, and determining congestion, nephritis and hæmorrhage
(Schütz). The _ovaries_, when tuberculous, lead to nymphomania and
sterility; they become swollen, with rounded projections, indurated, and
on section show all stages of infiltration, caseation and calcification.
They may encrease to a great size. Tubercles are found on the _Fallopian
tubes_, the _serous and mucous surfaces of the womb_, and in the _broad
ligaments_, in all their characteristic forms. The _bladder_ and
_vagina_ are less frequently involved. In the male the _testicle_,
_epididymus_, _tunica vaginalis_ and _prostate vesicles_ are sometimes
affected. The swelling and induration of the affected organ, or the
existence of hydrocele, may be noted.
_Tubercle of the Udder._ From the mass of blood passed through the udder
it is specially exposed to infection whenever the bacilli enter the
circulation. It may also be directly infected by the entrance through
the teat, or a trauma, of the bacillus of the stable dust. There may be
for a time only a slight general swelling which leads to no suspicion on
the part of the milker, and as the secretion is not arrested, a
dangerous product may be distributed. At this stage the lobules on
section appear swollen, gray, with paler or yellowish points and minute
hæmorrhages. The milk ducts contain coagula and bacilli (Bang). In other
cases, usually more advanced, the gland is hard, nodular, enlarged, and
shows a marked thickening of the walls of the smaller milk ducts and
secreting follicles, with yellowish and even caseous and calcified
centres. The gland is often greatly enlarged, the milk suppressed or
completely altered, and tubercular neoplasms or ulcers exist in the
larger ducts.
_Tuberculosis of the Brain and Spinal Cord._ As noted in Volume III.
this occurs in young cattle especially in the form of tubercles of all
ages attached to the pia or arachnoid, on the brain, or cerebellum, or
in the ventricles, also in the cerebral matter, in or on the lumbar
enlargement of the cord or on its pia. Several cases have come under my
notice in the mature cow.
_Tuberculosis of the Eye._ This has been seen mainly as a result of
experimental inoculation, yet casual cases also occur in the cornea,
sclerotic, iris or choroid, the product undergoing early necrosis and
softening into a yellow mass filling the different chambers.
_Tuberculosis of the Bones._ Though less frequent than that of internal
organs this is not rare. It usually attacks the spongy tissue, near the
articular extremities, or the vascular line between epiphysis and
diaphysis, giving rise to considerable exudate, thickening of the bone
and arthritis. The vertebræ, ribs, sternum, petrous temporal, frontal
and occipital also suffer. Sections of the bone show dilatations of the
cancelli, filled with the characteristic nonvascular groups of giant,
epithelioid and lymphoid cells with, at times, softened and caseated
centres. The adjacent bone is congested and softened, so that the
detachment of epiphysis and apophyses is not uncommon. In case of
invasion of the joints the cartilages and ligaments are the seat of
tubercular deposits, softening, fibroid change and caseation, and there
is general synovitis. The cartilages of the ear (concha) and nose
(septum) may also be invaded.
_Tubercles of the Skin._ These are not very uncommon in cattle being the
counterpart of the tuberculous warts and ulcers of the hands of
butchers, tanners and others that handle the products of diseased
animals. They may show as little pea-like nodules in the substance of
the skin, or immediately beneath, very commonly on the side of the
abdomen, where their presence in life furnishes a useful suggestion, as
enlarged masses forming raw, warty projections with centres of
caseation, or as clusters of warty-like growths of this kind (grapes).
_Tuberculosis of the Muscles._ This is comparatively rare in cattle,
though by no means unknown, appearing as tubercles of the size of a pea
and upward, in or between the muscular masses, often showing a caseated
centre.
_Tubercle of Lymph Glands._ No organs in the body suffer more than the
lymph glands as they receive through their afferent trunks and develop
the bacilli coming from any adjacent tissue to which they are
subsidiary. There is also evidence to show that bacilli entering from
the lungs or bowels may pass through these without apparent effect to
develop in the connected lymph glands. The frequent infection of the
pharyngeal, bronchial, mediastinal and mesenteric lymph glands has been
already sufficiently noticed, and if the other groups suffer less it is
mainly because the tissues from which they derive their lymph are less
frequently infected. An intimate knowledge of the different groups of
lymph glands is a most essential prerequisite to the diagnosis of
tuberculosis in life, and no less to a satisfactory _post mortem_
examination. The order of relative susceptibility and importance is
somewhat as follows: Bronchial, mediastinal, mesenteric, hepatic,
sublumbar, mammary inguinal, subdorsal, phrenic, intercostal (especially
the first and second), pharyngeal, parotid, submaxillary, prescapular,
prefemoral (stifle), prepectoral, axillary, cubital and popliteal.
_Relative Frequency of Tubercle in Different Parts in Cattle._ The
following table gives the seat of tubercle as noted by a number of
observers. It is open to the objection that it is the result of
examination for diagnosis, and therefore gives the most obvious rather
than the complete list of lesions. Examination of the brain, bones, deep
muscles and intermuscular glands, etc., was usually omitted. Again, as
the animals were often steers, the indications as regards the generative
organs are unreliable. The œsophagostoma nodules on the bowels have been
so often mistaken for tubercles that I have omitted all reference to
intestinal tubercle.
DISTRIBUTION OF TUBERCLES IN DIFFERENT ORGANS OF CATTLE: PER CENT OF
AFFECTED CATTLE.
────────────┬─────┬───────────┬────────┬──────────┬──────┬───────
│ % │ │ │ │ │
│Right│ % │% Costal│ │ │
│Lung.│Mediastinal│Pleura. │ │ │
│ % │ Glands. │ % │ % │ │
│Left │% Bronchial│Visceral│Mesenteric│ % │ %
│Lung.│ Glands. │Pleura. │ Glands. │Liver.│Spleen.
────────────┼─────┼───────────┼────────┼──────────┼──────┼───────
German │ │ │ │ │ │
Abattoirs,│ 75 │ 29 │ 47–55 │ │ 28 │ 19
Pearson, │ │ │ │ │ │
(Penna), │63–57│ 60.7–33.8 │ 22 │ 23.25 │ 20.7 │ 5.7
Bryce │ │ │ │ │ │
(Canada), │77.27│ 56.8 │ 11.36 │ 11.36 │ 40.9 │
Reynolds │ │ │ │ │ │
(Minn. │ │ │ │ │ │
Agr. Ex. │ │ │ │ │ │
Station), │89.4 │ 33.3–64.9 │ 79 │ 12.5 │ 35.4 │ 27
Law (N.Y. │ │ │ │ │ │
Grade │ │ │ │ │ │
Herds), │34.8 │ 64 │ 6.4 │ 9.6 │ 1.6 │
Nelson (N. │ │ │ │ │ │
J. Exp. │ │ │ │ │ │
Station │ │ │ │ │ │
Cows), │33.9 │ │ │ │ 28 │
Russell │ │ │ │ │ │
(Wis. Exp.│ │ │ │ │ │
Station), │ 55 │ 72.4 │ │ 24 │ 10 │
Stalker & │ │ │ │ │ │
Niles (Ia.│ │ │ │ │ │
Exp. │ │ │ │ │ │
Sta.), │ 36 │ 61 │ │ │ 8.3 │
Reick │ │ │ │ │ │
(Leipsic),│ 100 │ │ [2]57 │ │ 83 │ 18
────────────┴─────┴───────────┴────────┴──────────┴──────┴───────
────────────┬───────┬───────┬───────┬───────────┬──────────┬──────────
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
│ │ % │% Liver│ │ % │
│ % │Lumbar │ Lymph │ % │Pharyngeal│ %
│Uterus.│Glands.│Glands.│Peritoneum.│ Glands. │Diaphragm.
────────────┼───────┼───────┼───────┼───────────┼──────────┼──────────
German │ │ │ │ │ │
Abattoirs,│ 10 │ 5 │ 1 │ │ 4 │ 0.2
Pearson, │ │ │ │ │ │
(Penna), │ 5.5 │ │ 10.3 │ 14 │ 15.15 │ 11.4
Bryce │ │ │ │ │ │
(Canada), │ │ │ │ 45 │ │ 2.27
Reynolds │ │ │ │ │ │
(Minn. │ │ │ │ │ │
Agr. Ex. │ │ │ │ │ │
Station), │ │ │ 8.3 │ │ 18.7 │
Law (N.Y. │ │ │ │ │ │
Grade │ │ │ │ │ │
Herds), │ │ │ │ 17.7 │ 6.4 │
Nelson (N. │ │ │ │ │ │
J. Exp. │ │ │ │ │ │
Station │ │ │ │ │ │
Cows), │ │ │ │ │ │
Russell │ │ │ │ │ │
(Wis. Exp.│ │ │ │ │ │
Station), │ │ │ │ │ 31 │
Stalker & │ │ │ │ │ │
Niles (Ia.│ │ │ │ │ │
Exp. │ │ │ │ │ │
Sta.), │ │ │ │ │ 5 │
Reick │ │ │ │ │ │
(Leipsic),│ │ │ │ [2]57 │ │
────────────┴───────┴───────┴───────┴───────────┴──────────┴──────────
────────────┬────────┬──────┬────────┬──────┬──────┬─────────
│ │ │ │ │ │
│ │ │ │ % │ % │
│ │ │% Iliac │Lymph │Lymph │
│ │ │ and │Glands│Glands│ % Lymph
│ % │ % │Inguinal│ of │ of │Glands of
│Stomach.│Udder.│Glands. │Udder.│Flank.│Shoulder.
────────────┼────────┼──────┼────────┼──────┼──────┼─────────
German │ │ │ │ │ │
Abattoirs,│ 0.16 │ 1 │ 0.06 │ │ │
Pearson, │ │ │ │ │ │
(Penna), │ 7.2 │ 8.75 │ │ 13.5 │ 9 │ 7.75
Bryce │ │ │ │ │ │
(Canada), │ │ │ │ │ │
Reynolds │ │ │ │ │ │
(Minn. │ │ │ │ │ │
Agr. Ex. │ │ │ │ │ │
Station), │ │ 16.6 │ │ │ │
Law (N.Y. │ │ │ │ │ │
Grade │ │ │ │ │ │
Herds), │ │ 6.4 │ │ │ │
Nelson (N. │ │ │ │ │ │
J. Exp. │ │ │ │ │ │
Station │ │ │ │ │ │
Cows), │ │ │ │ │ │
Russell │ │ │ │ │ │
(Wis. Exp.│ │ │ │ │ │
Station), │ │ 6.9 │ │ │ │
Stalker & │ │ │ │ │ │
Niles (Ia.│ │ │ │ │ │
Exp. │ │ │ │ │ │
Sta.), │ │ │ │ │ │
Reick │ │ │ │ │ │
(Leipsic),│ │ 17 │ │ │ │
────────────┴────────┴──────┴────────┴──────┴──────┴─────────
────────────┬────────────┬──────┬────────┬──────┬────────┬───────
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
│ % │ % │ % │ % │ % │ %
│Pericardium.│Heart.│Kidneys.│Bones.│Muscles.│Larynx.
────────────┼────────────┼──────┼────────┼──────┼────────┼───────
German │ │ │ │ │ │
Abattoirs,│ 0.9 │ │ 0.7 │ │ 0.1 │ 0.13
Pearson, │ │ │ │ │ │
(Penna), │ 8.2 │ │ 2.1 │ 0.4 │ │
Bryce │ │ │ │ │ │
(Canada), │ │ │ │ │ │
Reynolds │ │ │ │ │ │
(Minn. │ │ │ │ │ │
Agr. Ex. │ │ │ │ │ │
Station), │ │ │ 2 │ │ │
Law (N.Y. │ │ │ │ │ │
Grade │ │ │ │ │ │
Herds), │ │ │ │ │ │
Nelson (N. │ │ │ │ │ │
J. Exp. │ │ │ │ │ │
Station │ │ │ │ │ │
Cows), │ │ │ │ │ │
Russell │ │ │ │ │ │
(Wis. Exp.│ │ │ │ │ │
Station), │ │ │ │ │ │
Stalker & │ │ │ │ │ │
Niles (Ia.│ │ │ │ │ │
Exp. │ │ │ │ │ │
Sta.), │ │ │ │ │ │
Reick │ │ │ │ │ │
(Leipsic),│ │ │ 52 │ 9 │ 49 │
────────────┴────────────┴──────┴────────┴──────┴────────┴───────
Footnote 2:
All serosæ.
_Swine._ The _lesions_ in swine, though essentially like those in
cattle, differ in some particulars. The primary tubercles are more
commonly pharyngeal or intestinal and mesenteric, in keeping with
infection by ingestion; caseation will often proceed to liquefaction, so
that the tubercles appear like grumous abscesses with irregular outlines
and vascular growths on their walls; there is less tendency to
cretefaction than in cattle; the muscular and intermuscular tissues and
the lymph glands are far more frequently affected; ulceration of the
pharyngeal and intestinal mucosæ is more common. The lungs, liver,
spleen and visceral lymph glands are very subject to tubercle, the
kidneys, uterus and testicles somewhat less so, and the nerve centres
least of all. The serosæ are often involved and the seat of clusters of
vascular or caseated neoplasms (grapes). The bones and joints also
suffer, particularly in young growing animals.
_Horse._ The horse suffers much less frequently than cattle or swine,
probably largely because of his outdoor life, his better tone as the
result of muscular work, and the absence of the excessive milk secretion
which is secured from cows and of the dangers from ingestion that attend
on swine. Yet, according to Nocard, it is even more susceptible, and the
disease once established is liable to advance more rapidly to a diffuse
generalization. The _lesions_ in the lungs and abdominal cavity resemble
those of cattle, both in nature and abundance; tuberculous polypi and
ulcers are more common; the visceral lymph glands (bronchial and
mesenteric) are early and severely attacked; the liver and spleen suffer
extensively, the serosæ somewhat less so; lesions have been noted in the
vertebræ, skin and muscles (Cadiot). In rare instances tubercles have
been seen in the heart, and the aorta has been atheromatous (Cadiot).
Necrotic degeneration, caseation and cretefaction occur as in cattle.
_Sheep and Goat._ Tuberculosis is infrequent in the goat and especially
so in the sheep, owing perhaps largely to open air life and their
predilection for high, airy pastures. When inoculated they show a marked
susceptibility, and under favorable conditions they contract the
infection casually. The tubercles may be found in all parts of the
body,—lungs, thoracic lymph glands, intestines, mesenteric and sublumbar
glands liver, spleen, serosæ, lymph glands at large, vertebræ, etc.
There is less tendency to calcification than in the ox, the older
tubercles remaining in the caseated condition or bursting and forming
vomicæ. A common seat of casual tubercle in sheep is around the throat
or on the sides of the cranium or face.
More frequently than in cattle, verminous affections (œsophagostoma
columbiana, and venulosum in the bowels, stongylus filaria and rufescens
in the lungs, linguatula denticula in the mesenteric glands) are
mistaken for tuberculosis, hence the necessity for a careful
investigation into the nature of the neoplasm, the presence of the
tubercle bacillus, and the absence of the worms and their eggs. Except
in the case of the linguatula the lymph glands are little affected by
the worms.
_Dog and Cat._ The _lesions_ are often concentrated on the respiratory
or alimentary tract, but they have been noted also in the pharyngeal
glands, tonsils, posterior nares, serosæ, liver, pancreas, spleen, nerve
centres, ovary, uterus, testicle, epididymus, tunica vaginalis,
prostate, heart, aorta, bones and joints. They follow the regular
development of bovine tubercle, and caseation and cretefaction are
prominent features. These animals are especially liable to infection by
eating the left victuals from the plate of a consumptive owner, as well
as by devouring consumptive prey, and the primary lesions are to be
looked for along the line of the throat, bowels, liver and lungs. For
the dog Cadiot records caseating polypi and ulcers on the mucosa of the
larynx, trachea and bronchia, and Müller and Cadiot several cases of
pharyngeal caseating adenitis in the _dog_ bursting externally and
developing intractable fistulæ, having abundance of bacilli in the
discharge. These he attributes to expectorated virus from old standing
tubercles in the chest infecting the pharyngeal mucosa and indirectly
the lymph glands. The infection entering with the food and lodging in
the follicles of the tonsils would act in the same way, and infected
wounds received in fighting must also be quoted. _Cats_ suffer from
similar intractable sores, some of which may be traced to a tuberculous
origin. The lungs are often extensively hepatized and of a general pale
grayish color, but the early miliary lesions, the caseating and
cutaneous centres, the vomicæ often intercommunicating, the tuberculous
bronchial and mediastinal glands and the bacilli show the true nature.
Intestinal ulcers are common, especially on the agminated glands, and
small tubercles, in all stages of degeneration are met with in the
enlarged liver, the spleen, pancreas, kidney, etc.
_Apes and Menagerie Animals._ In these tuberculosis is common alike in
the thoracic and abdominal forms, and the lesions in the main are those
of domestic cattle.
_Chickens._ The _lesions_ are common in the abdominal cavity, the
intestines, liver and spleen being the most frequently attacked, while
the subcutaneous connective tissue, bones and joints also suffer. The
lungs and kidneys usually escape. The intestinal mucosa shows small
nodules, often caseated, or ulcers; the enlarged and friable liver is
studded with tubercles from the size of a hemp seed upward, gray or
translucid, homogeneous or with central necrosis, simply or in
conglomerate masses, with congested or hæmorrhagic periphery; the spleen
is swollen and permeated by similar deposits; fibrinous ascitis is not
uncommon; the abdominal lymph glands are enlarged and congested.
The early tubercle shows a central, necrotic, hyaline area, consisting
of the debris of disintegrated cells, which is colored brown by picro
carmine, unlike the nucleus of the pheasant tubercle (Cadiot). Around
the hyaline centre is a zone of large epithelioid cells, the nuclei of
which stain strongly in carmine. Outside this is the usual zone of
small, round, lymphoid cells. In the whole the tubercle bacilli can be
made manifest by the carbol-fuchsin (Ziehl-Neelsen) stain. In the older
and larger tubercles the central necrotic mass has encroached in part or
in whole on the epithelio-lymphoid zone.
_Pheasant._ The _lesions_ have the same seats and naked-eye aspect as
the chicken tubercle, but under the microscope the smallest and most
recent tubercles show epithelioid cells to the centre, or later, the
central zone presents a dense fibrous network enclosing open spaces and
giving a mahogany stain with Lugol’s solution (iodine and potassium
iodide). (Cadiot). There has been an organisation of connective tissue
which has submitted to amyloid degeneration, making a clear distinction
from the tubercle of chicken.
_Parrot._ The _lesions_ were thus located by Eberlein and Cadiot:
│ Cadiot.│Eberlein.
Eye and periocular region, │ 12│ 14
Commissure of the beak, │ 7│ 11
Tongue, │ 8│ 9
Palate, │ 4│ —
Larynx, │ —│ 2
──────────────────────────────┼──────────────────────────────┼─────────
Bones and Articulations, │Upper limbs (wings), 7│ 14
„ │Claws, 3│ —
„ │Cervical, Dorsal and 5│ —
│ Caudal, │
──────────────────────────────┼──────────────────────────────┼─────────
Lungs, │ │ 7
Liver, │ │ 4
Intestine, │ │ 3
Muscles, │ │ 1
Heart, │ │ 1
The _skin lesions_ are vascular neoplasms containing bacilli and usually
invested with a covering of horn, but sometimes, on the legs and feet
raw. The morbid growth may be rounded or conical, narrowing to a point.
The _lesions of the buccal mucosa_ begin as small, grayish swellings on
the angle of the mouth, palate, tongue or larynx which grow out into
more or less rounded vegetations. The _lesions of the liver and lungs_
are mostly miliary with the usual tubercular features, but they may grow
to larger size, as a pea or bean. In the _cancelli of bones_ and on
their surface, the lesions resemble those of the mammal.
The cutaneous form has been held to be the counterpart of warty lupus of
man, the more plausibly that the disease is developed by inoculation
from tuberculous men. The arthritic type represents what is described as
gout in parrots.
In any case the recent miliary lesion presents the true tubercular type
of a central giant cell or cells with bacilli, surrounded by epithelioid
cells, and they in turn by small, rounded lymphoid globules.