Comparison of metastatic phenotypes in mammary tumours of the dog and cat.

Forty-eight canine and 57 feline mammary carcinomas with the corresponding lymph node metastasis were available for immunohistochemical analysis using a panel of antibodies (anti-ER, -PR, c-erbB-2, -P63, -CK14, -CK5/6, -CK19). The tumours and metastases were classified, according to a standardized algorithm, into one of the following 5 phenotypes, namely Luminal A and B; non-luminal: c-erbB-2 over-expressing, basal-like, normal-like. Canine primary tumour phenotypes evidenced a higher prevalence of luminal carcinomas (30/48) (P<0.05) while the cat showed a majority of c-erbB-2 over-expressing (22/57) (P<0.05). In lymph node metastases a significantly higher frequency of non-luminal phenotypes was evidenced in both species (P