الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Respiratory troubles continue to be a major problem for the horse industry and constitute a source of economic loss. Excess production of reactive oxygen species (ROS) is involved in the pathogenesis of airway disorders. Trace elements like copper (Cu), zinc (Zn), manganese (Mn), iron (Fe) and selenium (Se) are necessary for antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) acting as cofactors for these enzymes to assist the free radical scavenging activity and to protect the body from oxygen free radicals produced during oxidative stress. To evaluate the oxidative stress produced during respiratory tract diseases, venous blood samples were obtained from 115 native breed horses exhibited clinical signs of respiratory tract disorders in three occasions; before, 2 weeks and 4 weeks following treatment, respectively, in addition, 25 native breed horses were randomly selected and considered as a control group. Ten (acute) and Ten (chronic) of these horses were treated with traditional treatment, whereas, other Ten (acute) and Ten (chronic) of these horses were treated with traditional treatment in addition to antioxidants, including vitamin E selenium combination and vitamin C. To assess the antioxidant status, Cu, Zn, Mn, Fe, Se, low density lipoprotein (LDL) and malondialdehyde (MDA) levels were measured in serum of these horses. In addition, hydrogen peroxide (H2O2) level and activity of glutathione reductase (GR), CAT, glutathione-S-transferase (GST) and SOD were measured in the plasma of these horses.
In the diseased horses there was a significant decrease in the levels of Cu, Zn, Fe and Se and in the activity of CAT and GST. Meanwhile, there was a significant increase in Cu/Zn ratio, in the levels of Mn, LDL, MDA and H2O2 levels and in the activity of GR and SOD. Regarding of post treatment results, groups treated with traditional treatment plus antioxidants showed a significant improvement in general health condition when compared with groups treated with traditional treatment only. Moreover, antioxidants supplementation resulted in improvement of the antioxidant status of these horses. Vitamin E, selenium and vitamin C supplementation resulted in a significant increase in the levels of Cu, Zn, Fe and Se and in the activity of CAT and GST. Meanwhile, Cu/Zn ratio the levels of Mn, LDL, MDA and H2O2 levels and the activity of GR and SOD were significantly decreased. In conclusion, it could be concluded that there was a significant correlation between oxidative stress and both lung function and airway inflammation. So, antioxidants are suggested to be a therapeutic aid for respiratory troubles in horses as it is not only helpful in repairing the oxidative damage resulted from the effect of free radicals, but also for regaining the tissue healthiness.