Serum 8-hydroxy-2-deoxyguanosine as a marker of DNA oxidative damage in horses with recurrent airway obstruction

Background: It has been reported that equine recurrent airway obstruction (RAO) is a state of oxidative stress. Oxidant-antioxidant imbalance is known to increase the conversion of deoxyguanosine to 8-hydroxy-2-deoxyguanosine (8-OHdG) in DNA. 8-OHdG can easily be measured using ELISA tests in serum or urine samples. In this study, we analysed serum 8-OHdG levels in horses with recurrent airway obstruction and in healthy controls. Results: The study material consisted of seven healthy horses and seven horses with symptomatic RAO. All horses were exposed to moldy hay and straw for 48 h to induce clinical exacerbation of RAO. The serum 8-OHdG levels were determined using the ELISA Highly Sensitive 8-OHdG kit. The difference between the levels of 8-OHdG in healthy and RAO-affected horses was significant. The median level of 8-OHdG was 0.044 ng/ml in the healthy controls versus 0.498 ng/ml in RAO horses (P = 0.0021). Conclusions: The results of the study strongly suggest that DNA damage coexists in the course of equine RAO. We therefore propose that future research should aim at the development of new drugs that target pro-inflammatory molecules, since DNA damage appears to be the result of chronic inflammation.