Increased Oxidative/Nitrosative Stress in Bitches with Several Tumors

Experimental and clinical data suggest that reactive oxygen species, which cause no damage under physiological conditions, can cause cellular damage at high concentrations and may play key roles in carcinogenesis. The aim of this study was to evaluate the activities of catalase, superoxide dismutase, and glutathione peroxidise, as well as the production of malondialdheyde and nitric oxide, in bitches suffering adenocarcinoma, histiocytoma, and hemangiopericytoma. Data showed that the levels of both malondialdheyde and nitric oxide were significantly increased in both plasma and tissues. The decreased activities of antioxidant enzymes and increased oxidative stress observed could be attributed to a reduction in antioxidant defenses of the organism because of depleted defenses over time.