Feline mammary carcinoma shares many epidemiological and histopathological characteristics with human breast cancer, in particular, the human epidermal receptor-2 (HER-2) positive and triple negative (TN) subtypes, having been proposed as a suitable model for their study4–6, and offers further opportunities for studying certain aspects of tumor biology, such as the crosstalk between the immune system and tumor development. Here, ERBB2 is linked to breast cancer.