SERIAL DETERMINATION OF ANTIOXIDANT CAPACITY IN DOGS WITH NATURALLY OCCURRING GASTRIC DILATION-VOLVULUS

The ischemia-reperfusion seen in dogs with gastric dilatation-volvulus (GDV) could cause oxidative stress, decrease antioxidant capacity, and predispose patients to higher morbidity and mortality. Elevated lactate levels in dogs with GDV have been previously found to be a negative prognostic indicator. The purpose of this study was to serially evaluate oxidant and antioxidant concentrations in dogs with GDV and to determine if there is a correlation between the degree of antioxidant depletion and lactate levels. Dogs presenting to the Tufts Emergency Service that had not been treated with corticosteroids or fluids prior to admission and were not receiving antioxidant supplementation were eligible for the study. Blood samples were collected at the time of initial catheter placement pre-operatively (Time 0), and then 24 and 48 hours after surgery. The samples were analyzed for concentrations of oxidants [malondialdehyde (MDA), oxygen radical trapping capacity (ORAC) and F2 isoprostanes] and antioxidants (α-tocopherol, γ -tocopherol, vitamin C, and glutathione peroxidase). ANOVA with repeated measures was used to evaluate differences in the variables over the 48-hour period and Pearson correlation analysis was used to assess the relationship between 2 continuous variables. To date, 8 dogs have been enrolled in the study (1 female and 7 males, with a mean age of 8.0±2.2 years). All dogs have survived to discharge. The chart below indicates differences in parameters measured during hospitalization. Variable Time 0 median (range) 24 hours median (range) 48 hours median (range) P Value MDA (nmol/L) 0.725 (0.532–1.250) 0.500 (0.423–0.870) 0.512 (0.388–0.890) 0.008 α-tocopherol (ug/ml) 16.350 (3.800–29.400) 11.300 (6.760–30.800) 12.950 (7.850–40.400) 0.000 γ-tocopherol (ug/ml) 0.402 (0.138–0.776) 0.293 (0.000–0.500) 0.300 (0.000–0.503) 0.501 Mean plasma lactate upon admission was 4.3 mmol/L (range 2.1–7.2 mmol/L). There was a positive correlation between γ-tocopherol and lactate (r=0.784, P=0.012) but there were no correlations between lactate and MDA or α-tocopherol. Additional dogs are currently being enrolled in the study and analyses of the other variables (ORAC, F2 isoprostanes, vitamin C, and glutathione peroxidase) are pending. These preliminary results support the hypothesis of alterations in oxidant and antioxidant parameters in dogs with GDV.