Leukemia of Mammals. 869 



4. Leukemia. Leukaemia. 



{Leucocytemia; Leukdmische Lymphadenie [German]; Leuco- 

 cythemie, Lymphadenie [French].) 



(a) Leukemia of Mammals. 



Leukemia of mammals is a severe and general systemic af- 

 fection or proliferation of tlie lymphoid or myeoloid tissue, as a 

 result of which, swellings of the blood and lymph-forming organs 

 develop and the number of white blood corpuscles increases 

 more or less, partly at the expense of the red blood corpuscles. 

 According to whether the increase affects the lymphocytes or 

 the leucocytes, two forms of leukemia are distinguished, namely, 

 the lymphatic leukemia and the myeologenous leukemia (L. 

 myeloides). 



History. The first descriptions of the . disease were given inde- 

 pendently of each other in 1845, by Virchow in Berlin, and Bennett 

 in Edinburgh. By Virchow it received the name by which it is Jmown 

 at the present "Leukemia" (^«''ko's= white, «^/^«^blood) . The con- 

 nection between the affection of the spleen or the lymph glands and 

 the increase of white blood corpuscles was early recognized by Virchow, 

 the part of the bone marrow however was first established by Neumann 

 in 1899. 



Leisering was the first to recognize in 1858 the disease in animals, 

 but greater attention was paid to it only in the last two decades, so 

 that at present quite a number of positive cases are known. Siedam- 

 grotzky (1878), Johne (1879), Nocard (1880), Frohner (1885), Wolff 

 (1892), de Jong (1903), have carefully studied the disease, likewise 

 Hutyra and Marek, whose case was not published in detail. 



Occurrence. Leukemia occurs most frequently among dogs, 

 more rarely horses, cattle, hogs and cats are affected, whereas 

 nothing is known of leukemia in sheep and goats. Some of 

 the eases recorded in literature very probably do not belong 

 here, but to pseudo-leukemia or to tuberculosis. 



Sommer reported 46 cases up to 1889, of which 22 occurred in dogs, 10 in 

 horses, 7 in cattle, 5 in hogs and 2 in cats. Among the horses of the Prussian 

 army 2-4 cases occur annually. 



Etiology. The leukemia of mammals is probably of a 

 toxic-infectious origin, although nothing positive is known rela- 

 tive to this at the present time. The course of the disease 

 would correspond with this view, as well as its localization 

 in the various organs, but to date it has been impossible to 

 produce the disease artificially in mammals by feeding af- 

 fected organs (Nocard), or by subcutaneous or intravenous 

 inoculation of emulsions from organs (Mosler, Bollinger, Cadiot, 

 Roger, Gilbert, Marek). The bacteriological examination of 



