170 The Lymphocyte and Lymphocytic 1 issue 



animal is first presented for diagnosis or is first observed to be ill. This 

 "presenting" lesion affords a means of making interesting comparisons be- 

 tween species and may determine the significant signs and course of the 

 disease. 



Upon reviewing 147 cases of canine malignant lymphoma from the files 

 of the Angell Memorial Animal Hospital, it was found that in 65 per cent 

 of the cases, the presenting lesion was generalized lymphadenopathy (Fig. 



Fig. 13-7. Canine malignant lymphoma. A large mass in the wall of the ileum of a 6- 

 year-old male German shepherd clog. (Courtesy of Angell Memorial Animal Hospital.) 



13-6). In 12 per cent the thoracic lymph nodes were initially involved, result- 

 ing in respiratory difficulty. Single lesions in the small intestine (Fig .13-7) in 

 5 per cent of the cases resulted in obstruction or stasis of the intestinal tract. 

 Large masses in the spleen (Fig. 13-8) were the initial lesion in 2 per cent 

 of the cases, although early infiltration of lymph nodes was usually present. 

 In only 2 per cent was a leukemic blood picture observed, and this was 

 usually seen only in the terminal stages of the disease. Renal lesions were 

 outstanding in only 2 per cent of the canine cases. 



The incidence of malignant lymphoma among dogs admitted to the Angell 

 Memorial Animal Hospital increased slowly from 0.4 in 1948 to 1.54 per 

 1,000 admissions in L953. During the next five years, 1954 through 1958, 



