Vascular endothelial growth factor (VEGF) and metalloproteinase (MMP) 2 and 9 are useful biomarkers in human lymphoma. During cancerogenesis, transforming growth factor beta (TGF-β) stimulates VEGF and MMPs production. VEGF and TGF-β plasma levels were tested by ELISA, MMP-2 and MMP-9 by gelatine zymography in 37 dogs with lymphoma, 13 of which were also monitored during chemotherapy. Ten healthy dogs served as control. Lymphoma dogs showed higher act-MMP-9 (P < 0.01) and VEGF (P < 0.05), and lower TGF-β than controls, and a positive correlation between act-MMP-9 and VEGF (P < 0.001). Act-MMP-9 and VEGF were significantly higher in T-cell lymphomas, and in stage V compared with stages III–IV disease, regardless of immunophenotype. VEGF was higher in high-grade compared with low-grade T-cell lymphomas. No correlation was found between cytokines levels at presentation and outcome. During chemotherapy, act-MMP-9 and VEGF decreased in B-cell lymphomas (P < 0.01), suggesting a possible predictive role in this group of dogs.