Naturally occurring lymphoblastic leukemia in guinea pigs.

Nine cases of lymphoblastic leukemia were observed in 4,500 guinea pigs from three guinea pig production colonies during a period of 3 years. Seven of the cases occurred in strain 2/N, one in 13/N and one in Dunkin-Hartley/FD. These guinea pigs were 5.5-29 months old and included two males and seven females. Clinically, the animals showed a variety of signs, such as enlargement of peripheral lymph nodes, posterior paralysis and terminal ataxia. Gross lesions were characterized by numerous white spots and enlargement of the lymph nodes and many internal organs. Hematologic examination showed leukocytosis with lymphoblasts predominating. Histologic and cytologic examination of affected tissues and cells revealed generalized infiltration of lymphocytic leukemic cells.