CHAPTER VI.. Diseases of the Lymphatic System.

DISEASES OF THE LYMPHATIC SYSTEM.

Diseases of the lymphatics are numerous, highly important, and still imperfectly understood. They follow various accidents, local inflammations, certain specific diseases, such as tuberculosis, and may occur in an isolated form without involving any other part of the body.

Inflammation, usually of infectious origin, may attack lymphatic vessels (lymphangitis) or lymphatic glands (adenitis), giving rise either to simple lymphangitis, suppurative lymphangitis, or again to simple or suppurative adenitis.

It is unnecessary to emphasise this point in general surgical pathology, for it is identical with that which is observed in other domestic animals, but in order properly to detect the glandular symptoms in certain diseases peculiar to the lymphatic apparatus, and in certain specific diseases, such as tuberculosis, farcy of the ox, etc., it is necessary to understand thoroughly the topography of the lymphatic system.

=Topography of the lymphatic glandular apparatus: Examination.= The lymphatic glands are in some cases superficial, in others deep seated, and are arranged symmetrically on either side of the body.

Beginning with the head and fore quarters, the lymphatic apparatus comprises a subglossal, a preparotid, a subatloid, a prescapular and several prepectoral glands (Fig. 209).

None of these glands are very deeply placed, and all are easily accessible to palpation, provided their exact position is known and the animals are not too fat.

The subatloid is a little more difficult to detect, but in thin animals the tips of the fingers can easily be passed under the wing of the atlas so that the condition of the gland can be examined.

In a normal condition, any gland on being examined conveys a sensation of softness and elasticity of a special character which never varies. Palpation is painless.

When, however, the gland is diseased, palpation causes pain in the case of all acute affections. It may, indeed, be impossible to reach the glands, as they are buried sometimes in œdematous swellings of varying size. On the other hand, they may be painless on being touched, but swollen, hypertrophied, indurated, hardened or caseous.

The deep-seated glands of the fore portion of the body comprise the retro-pharyngeal and the cervical chain running along the posterior border of the trachea. Normally these glands cannot be examined (Fig. 210); but when the seat of certain morbid processes, they may be so enlarged as even to be readily visible. The larynx and pharynx are then displaced downwards, the depression between the head and upper extremity of the neck disappears, together with the depression known as the jugular furrow. Such deformities may be either perfectly symmetrical, as in lymphadenia, or (as is more commonly the case) asymmetrical, as in tuberculosis; and if inspection leaves any doubt, the glands may be further examined by palpation.

To obtain the fullest information both hands should be used, one arm being passed over the neck and the fingers engaged behind the trachea. The operator may also stand in front of the animal, whose head should be lifted so that the points of the fingers can be thrust deeply inwards on either side of the trachea in the direction of the vertebral column.

In the posterior portion of the body the number of glands that can be examined is much smaller. The gland of the stifle, also called “gland of the flank,” is, so to speak, the only one which can readily be detected by examination or palpation. Nevertheless, in cases of lymphadenitis, tuberculosis of the glands, etc., it becomes easy to detect lymphatic glands in the loose fold of skin known as the flank. These glands are very small, and three in number. They are arranged in a triangle, one being much more prominent than the two others. In exceptional cases, little nodular glands, indistinguishable at ordinary times, may become hypertrophied. This is particularly true of the small glands in the neighbourhood of the last rib.

The retro-mammary glands need only be mentioned, but it is important to know that a deep-seated popliteal gland also exists above the semi-tendinosus and semi-membranosus muscle in the thickness of the muscles of the thigh; as also an ischiatic gland opposite the ischiatic notch, which can only be examined by internal palpation from the pelvis, and an anal gland situated deeply on the sides and in front of the sphincter ani.

With the exception of those of the pelvis and of the sublumbar region, the glands of the thoracic and abdominal cavity cannot be examined, but change in them is indicated under certain circumstances by clearly defined clinical symptoms, and moreover it is necessary to be able to detect changes in these glands on post-mortem examination.

In the thoracic cavity the lymphatic apparatus comprises the mass of the prepectoral glands, which extends into the anterior mediastinum between the first ribs (glands of the entry to the chest), the aortic lymphatic gland situated beneath the dorsal portion of the spine opposite the bifurcation of the aorta, and the lymphatic glands of the posterior mediastinum, one of which is relatively small and is lodged in the concavity of the posterior aorta, the other large, elongated and situated immediately above the œsophagus in front of its passage through the diaphragm.

In the abdominal cavity a sublumbar chain is found situated on the sides of the lumbo-sacral portion of the vertebral column, the mass of the subsacral lymphatic glands, and, at the entrance to the pelvis, extending on either side along the course of the external iliac arteries and veins and resting on the shafts of the iliac bones, the iliac glands.

All these glands are partly accessible to examination by the rectum.

Last of all, we may mention the gland situated on the hilum of the liver, the mesenteric glands, and the little lymphatic glands above the sternum.

In the front limb the only glands of importance from a clinical standpoint are those of the internal surface of the shoulder, close to the divisions of the brachial plexus.

When enlarged or invaded by any specific organism, they may, by compressing the nerve trunks, cause lameness.

THE LYMPHOGENIC DIATHESIS.

(LYMPHADENITIS, LYMPHO-CYTHÆMIA, MYELO-CYTHÆMIA.)

It has been questioned whether the term “lymphogenic diathesis,” which was employed in human medicine by Jaccoud to describe certain morbid conditions also found in animals of the bovine species, should continue in use. At the present moment it is difficult to determine the question. Under any circumstances it has the advantage of including diseases of the lymphatic system, indicated by hypertrophy of the lymphatic glands (adenitis) or by an exaggerated production of white blood corpuscles (leucæmia), and the passage into the general circulation of products derived from the lymphatic apparatus. For these reasons it may be employed here.

Clinical investigation long ago demonstrated that in man certain pathological conditions were characterised by a peculiar colour of the blood, due to the presence of white blood corpuscles in excessive quantities, whence the names “leucæmia” (Virchow) and “leucocythæmia” (Bennett). In the same way it has been shown that the change in the blood characterised by a superabundance of white blood corpuscles generally coincides with engorgement or more or less marked hypertrophy of the lymphatic system and of the adenoid tissue of the body (lymphatic glands, spleen, bone marrow, and, in exceptional cases, liver, kidneys, etc.)—leuco-cythæmic lymphadenitis; but that many cases also occur in which this hypertrophy of the adenoid tissue or of the lymphatic gland tissue may exist, without any excessive number of white blood corpuscles in the blood, whence the name “aleucæmic lymphadenitis or pseudo-leucæmia.” Cases of true leucæmia without adenitis are much rarer, the lesions therein being confined to the adenoid tissue of the bone marrow.

These three morbid conditions—leucæmic lymphadenitis, or leucocythæmia; aleucæmic or pseudo-leucæmic lymphadenitis, or more simply adenitis; and true or simple leucæmia—are frequently found in the bovine species. Whilst stating that these diseases are frequent, we must, however, be understood to except the numerous cases of tuberculous lesions formerly included under the same head.

Jaccoud has shown that in reality the causes of these three morbid conditions are very similar, and that a case which at first appears to be of the nature of aleucæmic lymphadenitis may later become transformed into leucæmic lymphadenitis; or, inversely, that a case which at first appeared to be a simple leucæmia might often become complicated with lymphadenitis: hence the grouping of these different morbid conditions under the heading of lymphogenic diathesis.

Investigations have now thrown more light on the subject because of the more perfect recognition of the varieties of white blood corpuscles, and the above-mentioned morbid conditions may be defined as follows:—

(1.) The first variety consists of a more or less marked adenitis or lymphadenitis without leucæmia (aleucæmic lymphadenitis).

(2.) The second variety, consisting of leucæmic lymphadenitis, or leucocythæmia, is a lymphatic lucæmia or lympho-cythæmia, the anatomical characteristic of which is enlargement of lymphatic glands, and the histological characteristic increase in number of the large and small lymphocytes.

(3.) A third variety, formerly regarded as simple leucæmia without lymphadenitis, is myelogenic leucæmia or myelo-cythæmia, the anatomico-pathological characteristic of which is to be found in myeloid hypertrophy of the bone marrow, giving to the bone marrow on post-mortem examination a puriform appearance, and in the myeloid condition of the spleen.

Histologically this variety is characterised by an absolute increase in numbers of the large mono- and poly-nuclear eosinophile leucocytes.

=Symptoms.= Simple lymphadenitis begins in an insidious manner, and is characterised by weakness, anæmia, paleness of the mucous membranes, and wasting without apparent reason, although the appetite is preserved. It is only at a later stage that the glandular enlargements are discovered (adenitis), and often this discovery is not made until the veterinary surgeon is called in.

The existence of the disease is indicated by enlargement of the superficial glands, and this enlargement, which may commence at any point, extends along the course of the lymphatic vessels to the neighbouring glands, until in a shorter or longer time it involves all the lymphatic glands in the body.

The enlargement of the glands is usually symmetrical, and on clinical examination it is sometimes easy to detect at the outset an increase in size of the retro-pharyngeal glands, the glands of the neck, the prescapular glands, the glands of the flank, etc.

Rectal exploration reveals hypertrophy of the glands of the pelvis and of the sublumbar region, etc. The animals waste very rapidly, and sometimes in a few months become incapable of standing. They develop cachexia, and die in a state of exhaustion, with no other lesions than those of lymphatic hypertrophy. Neither do they exhibit any marked increase in the number of white corpuscles in the blood.

In lympho-cythæmia the beginning of the disease is often identical with that of simple lymphadenitis, the increase in the number of white blood corpuscles not occurring until later. In other cases, on the contrary, leucæmia appears first, and the enlargement of the lymphatic gland follows; but what characterises this form and allows of it being distinguished from myelo-cythæmia is the great increase in the number of large or small lymphocytes. The development is identical with, and sometimes much more rapid than, that of the preceding form. The animals waste away and become anæmic and cachectic, dying at last in a state of absolute exhaustion.

Post-mortem examination reveals, as in the previous condition, symmetrical hypertrophy of all the lymphatic glands; the spleen is very often enormous, and the liver is sometimes affected, as are also, in exceptional cases, the kidneys.

It may happen that the spleen alone appears affected, or at least that it has been first attacked, a fact which explains the existence of leucæmia before any enlargement of the lymphatic glands.

=Causation.= The causes of lymphadenitis and of lympho-cythæmia are unknown in veterinary as in human medicine. Apparently these diseases are more common in adults than in young animals. Some regard them as infectious in character, but this can hardly be the case, as all experimental attempts to transmit the diseases have failed. It is more plausible to compare the development of these morbid conditions with that of malignant tumours, and although some doubt still exists, simple lymphadenitis may be described as an aleucæmic lymphoma or lympho-cytoma, which has gradually become generalised, spreading by way of the lymphatic channels from the gland first affected through the surrounding glandular system. Lympho-cythæmia, on the other hand, may be said to be a leucæmic lympho-cytoma, which spreads both by the blood circulation and by the lymphatic paths (spleen, hæmatopoietic glands and organs).

This view of the development of the lesions enables us to class lympho-sarcomata with lymphomata and lympho-cytomata. The malignant character and extremely rapid development of lympho-sarcomata appear due to its extending by contiguity of tissue, and simultaneously by the lymphatic paths.

This new grouping would consequently place on one side myelogenic leucæmia, also called myelo-cythæmia, which is perhaps a different morbid species. This would destroy the unity implied in Jaccoud’s theory of the lymphogenic diathesis; but for all that this method of grouping might be justified by reference to specific cellular characteristics. In myelo-cythæmia the disease appears to commence as a lympho-cythæmia, i.e., it is unaccompanied by enlargement of lymphatic glands or hypertrophy of the spleen or liver, though the blood appears leucæmic. The condition is not a leucæmia due to lymphocytes, but rather a leucæmia produced by mono- and poly-nuclear eosinophile leucocytes, i.e., leucocytes derived from the bone marrow.

The patients are carried off rapidly after persistent wasting, decline and cachexia, whilst on post-mortem examination the puriform aspect of the bone marrow is an extremely striking characteristic.

=Diagnosis.= There is rarely much difficulty as regards the diagnosis. The enlargement of the lymphatic glands, for instance, can readily be detected, and the only disease with which this can possibly be confounded is tubercular enlargement.

With the means at present available for diagnosing tuberculosis, such as microscopic examination of the discharge, inoculation with discharge, examination of material from the glands, injection of tuberculin, etc., the nature of the disease can always be placed beyond doubt.

In lympho-cythæmia and in myelo-cythæmia, the whitish-violet lactescent appearance of the blood is of unmistakable significance, particularly when the manifest progressive wasting of the whole system is taken into account.

Histological examination of the blood after fixation and staining will in the former cases reveal the presence of very large numbers of lymphocytes, and in the latter an absolute increase in the number of the mono- and poly-nuclear lymphocytes. It should be easy, therefore, to distinguish the two diseases, especially as other symptoms vary.

In the early stages leucæmia may be mistaken for the leucocytosis seen in infectious diseases. These forms of leucocytosis are very common in animals of the bovine species. They occur in certain forms of tuberculosis, in uterine infections, in cases of internal suppuration, in tumour of the heart, the rumen, etc., and vary in so far as one style or another of white blood corpuscle predominates. The diagnosis, therefore, necessitates that the white blood corpuscles should be counted, and whenever it is found that their variations in number are no more than between 5,000 and 15,000 per cubic millimètre, the case may be regarded as one of temporary leucocytosis.

If, on the other hand, those corpuscles number more than from 15,000 to 20,000, or, as may sometimes happen, they attain to from 200,000 to 300,000 per cubic millimètre (one white to two or three red blood corpuscles), the case is one of leucæmia, and, according to the predominance of the particular type of cell, it is a lympho-cythæmia or a myelo-cythæmia.

In leucæmic conditions the red blood corpuscles are also present in fewer than the normal numbers. They are more irregular, assume giant and dwarf forms (macrocytes and microcytes), sometimes exhibit lacunæ, and are always polychromatophile, i.e., without special affinity for any particular constituent of double or triple stains.

=Prognosis.= The prognosis of diseases included in the lymphogenic diathesis is extremely grave, and in the present state of our knowledge it may be assumed that sooner or later death is inevitable.

=Treatment.= Treatment can scarcely be considered to exist, for at the best it can only delay the development of the disease. Nevertheless, and with this reservation, it is certain that preparations of iron, iodine and arsenic have a certain effect, probably by acting on the hæmatopoiesis.

CASEOUS LYMPHADENITIS OF THE SHEEP.

In the sheep the lymphatic glands are sometimes the seat of peculiar changes, which do not appear to have any marked effect on the general condition. Thus a post-mortem examination or an examination of animals in the slaughter-house sometimes shows a certain number of isolated or symmetrical glands, such as the mediastinal, tracheal, inguinal, pelvic or sublumbar glands, to be greatly enlarged and completely degenerated. The precrural, prescapular, and popliteal glands are said to be most frequently affected. Their contents are caseous and yellowish, enveloped in a fibrous sheath, and show no signs of peripheral inflammation. The other organs and viscera may either be healthy or exhibit caseous lesions identical with those found in caseous broncho-pneumonia.

=The causes= of this disease are imperfectly understood, although Cherry and Bull (1899, the Veterinarian, Vol. LXXII., No. 860, p. 523) have isolated from the lesions an organism identical with Preisz’s bacillus and with the microbe of ulcerative lymphangitis in the horse.

Norgaard and Mohler (Annual Report, United States Bureau of Agriculture, 1899, p. 638) have studied the disease. In June, 1897, Turski, at Danzig, found about 150 breeding ewes, from eight to twelve years old, suffering from nodules or abscesses the size of a child’s fist in the inguinal and prescapular regions. They had been sold for slaughter, and many were in very poor condition. The disease occurs in Europe, Western America, South America, and Australia. Several thousand cases are annually seen in the slaughter-houses of the United States.

=The symptoms= generally escape notice, and it is only by accident that one sometimes detects marked enlargement of the lymphatic glands of the neck or of the superficial inguinal glands. The patients, moreover, may remain in very good bodily condition, so that the lesions are only discovered on the meat being inspected.

Having regard to our imperfect knowledge of this disease, it is impossible to express an opinion as to its importance or treatment.

GOITRE IN CALVES AND LAMBS.

Although not strictly relevant to the foregoing matter, a few remarks may here be made on the subject of goitre.

True goitre consists in hyperplasia of the follicles of the thyroid gland, with colloid change of their contents, which are chiefly albuminous. The swelling is mainly due to enlargement of the follicles, and is termed struma follicularis. It may attack the entire organ or only one-half; less frequently it is confined to certain sections. Other varieties of goitre are recognised, such as fibrous, varicose and cystic goitre. (For fuller details see Möller and Dollar’s “Regional Surgery,” p. 149.)

=Treatment= by injection of thyroid juice or by feeding on thyroid extract has given better results than drugs.

The following account of an outbreak in New Zealand is summarised from the Annual Report of the Chief Veterinarian of New Zealand, 1901:—

The calves affected were born with enlarged thyroids. The farm is of rich alluvial deposit, and rather below the level of the river, which it borders. The land has been in occupation, however, for many years, and no similar condition had been previously noted. At first, as calves only were affected, it was thought possibly to be due to the bull, a two-year-old animal, but when a foal was born suffering from a similar malformation this theory naturally fell to the ground.

The land had been ploughed with a special plough 20 inches deep, but this is no uncommon practice in the island.

About the same time, a similar disease was discovered affecting lambs at a farm near Outram. From 450 ewes, 150 lambs had been lost, the glands being enlarged to the size of a cricket ball. A few had been born dead, many only lived a few hours, others lived several days, and a considerable number recovered. There was no connection, directly or indirectly, between the two farms, they being at least fifty miles apart. A few of the calves died or were killed, the remainder recovered, and the foal grew rapidly better. The land on both farms is very similar in composition.

Mr. Wilkie states, from observation of previous cases in lambs, that “it appears to be always associated with malnutrition and a condition of anæmia in the parent, induced in most cases by feeding with watery, innutritious foods.”

Specimens were forwarded, from a calf and from a lamb, of enlarged glands. The gland of the calf was enormously enlarged, being at least twice the size of an orange, dark in colour, flabby in consistency, and on section a mucous material exuded copiously from the cut surface. Micro-examination showed the acini to be larger than normal, filled with the usual mucous material, and lined with cubical epithelium. The connective tissue surrounding the alveoli was, however, crowded with round-cells, so much so that the whole parenchyma seemed to be practically composed of these cells.

A specimen of an enlarged thyroid from the lamb was about the size of a sheep’s kidney, and very much the same shape and colour. Sections microscopically examined showed a different condition to that of the calf’s thyroid. Here the acini were filled with epithelial cells loosely arranged as if the lining epithelium had been proliferating rapidly, while the connective tissue surrounding the acini was fairly normal. The section had a somewhat adenomatous appearance.