Considering our previous results showing that cats with mammary carcinoma have higher circulating levels of several immunomodulatory molecules (IL-6, TNF-α, CTLA-4, PD-1, PD-L1, VEGF-A, VEGFR-1, VEGFR-2, and LAG-3) [33,34,35], the serum TIM-3 levels were evaluated to check for statistical correlations. This evidence concerns the gene CTLA4 and breast carcinoma.