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).