Canine mammary carcinoma cells response for ghrelin was completely abolished after pre-treatment with specific inhibitor of GHS receptor ([D-Lys3]-GHRP6). The canine mammary cancer cells viability determined by MTT assay in control conditions (CTR) and in one hour pre-incubation with specific inhibitor of GHS receptor ([D-Lys3]-GHRP6) at concentrations of 100 and 200 μM and following incubation with n-octanoylated ghrelin peptide (10 nM) (Peptides International) for 24 hrs. Absorbance at 570 nm has been converted to percentages (±SEM). The experiment has been conducted in n = 15 repetitions. The pre-treatment with specific inhibitor of GHS receptor completely abolished the cells response for ghrelin treatment (10 nM) in the CMT-W1 (A), CMT-W1M (B) and CMT-W2 (C) cell lines, respectively. The statistical analysis was performed using Prism version 5.00 software (GraphPad Software, USA). One-way ANOVA followed by Dunnett’s post hoc comparisons were applied. No significant differences has been observed.