In the last years many scientific veterinary reports highlighted the pivotal role of nutrition also as a support in animals before surgical, chemotherapy and radiotherapy interventions. We aimed to evaluate the effectiveness of a dietary supplement named Gold Lotion (GL, 4 mL day for 6 months) as adjuvant of current pharmacological therapy in 18 cats affected by different tumors (digestive system lymphoma, carcinoma and cutaneous fibrosarcoma). Metabolic profile and oxidative stress parameters of cats resulted significantly improved after 6 months of GL supplementation (*p<0.05, **p<0.01). The combined use of GL and pharmacological therapy not only significantly ameliorated digestive and hepatic functionality of all cats and reduced the overall overload of free radicals but also improved their quality of life (QoL). Unfortunately the life span expectancy did not improve and all cats died few weeks later after GL supplementation interruption due to metastases spread and a consequent clinical condition severe worsening.