In this group of animals, the CXCR4 expression rate was significant higher in distant metastases (100%) and regional metastases (84.6%) than in PT (77.4%) (p = 0.012; OR = 6.40; 95% CI: 1.34–30.62), with cats with CXCR4 positive mammary carcinomas showing CXCR4 positive status in the majority of RM (10/11, 90.9%) and in all DM (4/4, 100%). The gene discussed is CXCR4; the disease is breast carcinoma.