Comparative Pathology of Lymphocytic Malignancies 163 



Of historic interest is the experimental transmission of the canine 

 venerea] tumor from a naturally infected dog to other dogs, which was ac- 

 complished in 1 876 by a Russian veterinarian, Novinsky. This feat 

 prompted at least one of Novinsky's countrymen to consider him "the fore- 

 lather of experimental oncology." An important milestone in research on 

 lymphocytic malignancies was passed in 1908 when Ellermann and Bang 

 experimentally transmitted fowl leukosis from affected to normal chickens, 

 although the disease had been described as a natural occurrence in birds as 

 early as 1868. 



Our purpose is to point out certain interesting features of this group 

 of diseases in birds, swine, horses, rodents, monkeys, and cattle and to make 

 more detailed comparisons between the dog and cat. (The disease of mice 

 is discussed in Chapter 12.) 



LYMPHOCYTIC MALIGNANCIES IN SPECIES 



Birds 



The term "fowl leukosis" is used to encompass the erythroid, myeloid, 

 and lymphoid malignancies of the domestic fowl. The erythroid and myeloid 

 forms are most readily induced experimentally in susceptible birds and 

 have been the subject of rather extensive laboratory study. The lymphoid 

 form of the disease is widespread in nature to the extent that it constitutes 

 an important economic problem. However, it is more difficult to induce in 

 the laboratory. Limitations of time preclude further consideration of this 

 avian disease, although it presents many interesting similarities as well as 

 differences in comparison with neoplastic lymphocytic disease in mam- 

 mals. 7 ' u 



Pigs 



Although some of the earliest reports on leukemia were devoted to swine, 

 the disease does not appear to be common, at least to judge from the litera- 

 ture. Swine are susceptible, however, and some well-documented cases are to 

 be found. la - 14 > 18 - 28 



Horses 



Malignant lymphoma occurs in this species, 2 '' but its frequency is un- 

 known. Decreased interest in these animals over the past three decades has 

 resulted in few studies of such a rare disease. It is possible that the present 

 growing interest in horses and ponies may make studies in the equine species 

 possible again. 



