Experimental transmission of canine malignant lymphoma to the beagle neonate.

Two serial passages of canine malignant lymphoma (CML) were accomplished in 2 litters of Beagle neonates with suspen sions of viable CML whole cells. In these experiments 3 of 15 dogs inoculated with a single dose of either a cell suspension or a cell-free extract developed malignant lymphoma at 50, 53, and 80 days postinoculation. Two dogs with overwhelming CML were preirradiated, while one dog was not X-irradiated. Thus, a significant feature of this work was the successful trans mission of CML without pretreatment of total-body irradiation. Malignant lymphoma did not occur in the third serial passage, although animals had enlargement of the superficial lymph nodes. Biopsies of these enlarged lymph nodes revealed lymphoid hyperplasia but not malignant lymphoma. The clinical signs and pathologic lesions were similar to those reported for naturally occurring malignant lymphoma of dogs and cats. Electron microscopic examination revealed intracytoplasmic structures which were made up of individual particles that measured 18 to 22 m/* in diameter.