Indeed, some clinical studies have shown that TOC treatment significantly decreased the number of circulating Tregs, and increased the plasma concentration of VEGF in dogs with tumors.14, 15 We found that TOC treatment inhibited VEGFR2 expression and decreased the number of HIF‐1α+ tumor cells and Foxp3+ Tregs within the tumor tissue, although little is known about the inhibitory mechanisms. This evidence concerns the gene HIF1A and neoplasm.