The case histories of 8 dogs with spinal pain and neurologic deficits associated with vertebral plasma cell tumor are reviewed. Four dogs had solitary plasmacytoma, 3 had multiple myeloma, and 1 dog had 2 vertebral lesions with no evidence of disseminated disease. Four dogs were treated: 2 with multiple myeloma received chemotherapy only and survived 17 and 26 months, respectively. Two dogs with solitary plasmacytomas of the spine had chemotherapy and radiotherapy: the 1st survived 4 months and was euthanized after developing radiation myelopathy; the 2nd survived 65 months before developing multiple myeloma. The diagnosis of solitary plasmacytoma of the spine versus multiple myeloma is discussed.