Recently, it has been demonstrated that erythropoietin (EPO) and its receptor are expressed in advanced solid tumor, and could be involved in human breast carcinoma growth. Pro-inflammatory cytokines TNF-α, IFN-γ and IL-1β are released in elevated inflammatory response and neo-vascularization tumor areas, and present remarkable synergism in human cell lines carcinomas. The aim of our study was to evaluate circulating concentrations of EPO, IL-1β, TNF-α and IFN-γ in dogs (n = 10) with histological diagnosis of mammary gland carcinoma and without evidence of metastasis. Ten aged-matched intact bitches served as control group (CG).

Sandwich enzyme immunoassays for the quantitative measurement for canine serum were used to quantify EPO and the cytokines (USCN Life Science Inc., China). Continuous variables were evaluated for normality followed by Tukey's post-hoc test, and differences were considered significant at p < 0.05.

Erythropoietin concentrations was higher in dogs with mammary carcinoma (4.42 ± 0.63 U/L) than healthy dogs (1.88 ± 0.33 U/L, p = 0.014). No significant difference was observed in IFN-γ and IL-1b between groups, but TNF-α concentration was higher in dogs with mammary carcinoma compared to CG (26.68 ± 3.43; 10.48 ± 2.61 pg/mL, respectively; p = 0.0043).

The most well-recognized alteration in pro-inflammatory cytokines is seen in human advanced carcinomas. In our study, we selected dogs to accesses the earliest possible inflammatory alterations associated with mammary carcinoma. In view of these data, we observed that EPO and TNF-α were already increased in early stages of canine mammary carcinoma, showing that even early stages were able to change homeostasis of the immune system, inflammation and host defense.