A 7-year-old, female neutered cross-breed dog was referred to our institution with a history of progressive hind limb weakness, which then progressed to paraplegia. An MRI of the spine revealed severe meningeal infiltrate consistent with lymphoma involvement, located at the level of L2-L7 with concurrent lymph node enlargement and abnormal bone marrow. Abdominal ultrasonography also identified changes in the spleen and confirmed enlargement of the lumbar aortic lymph node. Cytology of lymph nodes and spleen confirmed a high-grade lymphoma with features of a large granular lymphocyte (LGL) variant; PCR for antigen receptor re-arrangements (PARR) was positive for a clonal T-cell receptor rearrangement. The dog was started on a chemotherapy protocol with lomustine and cytarabine incorporation and had a rapid improvement in neurological status. Chemotherapy was continued until relapse and rescue treatment used at that time. The dog was euthanased at the time of recurrence of neurological signs, 195 days since medical treatment was started. This case report suggests that combination chemotherapy may be of use when treating LGL lymphoma with spinal involvement and survival time may potentially exceed 6 months.