In this research, serum activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase and total antioxidant capacity (TAC) of 37 cattle suffering from theileriosis were compared with 35 healthy ones. Mean± SD of all variables in patients and control animals were significantly different [SOD 7.07±1.26 vs. 10.70±1.98 u/mgHb (P=0.001), GSH-Px 2.33± 0.89 vs. 26.67± 0.497 u/mgHb and catalase activity 0.96±0.497 vs. 2.33± 0.89 u/mgHb (P=0.0001), respectively. Serum TAC of cases (0.71± 0.21 mmol/l) were significantly (P =0.001) lower than healthy group (1.62± 0.35 mmol/l). There was only a significant correlation coefficient relationship between serum catalase activity and TAC levels of affected cows (P=0.049, r=0.389). According to these results, oxidative enzymes activities and TAC could be dramatically decreased in this protozoan infection and it is concluded that improving this condition might accelerate treatment procedure.
