Background: This study was conducted to compare the changes in oxidative stress levels with some trace elements in blood serum in healthy bitches and bitches with transmissible venereal tumor (TVT). Methods: A total of 40 bitches were used in the study. According to the genital organ examinations, healthy bitches constituted the control group (n=20) and those with venereal tumors constituted the TVT group (n=20). Total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI) were determined spectrophotometrically. In addition, some serum trace element levels such as magnesium (Mg), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn) and selenium (Se) were measured using an ICP-MS analysis device. Result: The serum Se, Mg and Zn levels were lower in the TVT group compared to the control group (p less than 0.01) and serum Fe and Cu levels were higher in the TVT group than in the control group (p less than 0.01). Serum TOS and OSI levels were higher (p less than 0.001) and serum TAS levels were lower (p less than 0.001) in the TVT group compared to the control group. The study results showed that oxidative stress is high in bitches with TVT, and in parallel with this, changes occur in the amount of certain trace elements that are associated with oxidative stress.