The Oxidative Stress Markers of Horses—the Comparison with Other Animals and the Influence of Exercise and Disease

SIMPLE SUMMARY: Although oxidative stress is detrimental in biological systems, direct analysis of the active oxygen species that causes the stress has been difficult at a clinical level. In the current study, we analyzed the levels of diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) in the serum of horses. These are easy to measure and they provide information on the level of oxidative stress in an animal. The mean d-ROM level in horses was higher than those in dogs or dairy cattle, and the levels in horses can be used to distinguish those with a disease. ABSTRACT: Diacron-reactive oxygen metabolite (d-ROM) and biological antioxidant potential (BAP) levels in the serum of horses were measured (ponies, n = 15; thoroughbred, n = 31; other full-sized horses, n = 7). The mean d-ROM levels in horses were significantly higher (p < 0.001) than those in dairy cattle (n = 25) and dogs (n = 31). However, d-ROM levels in horses were lower than the standard levels reported in humans. When d-ROM and BAP levels were plotted graphically, the points for horses with a disease (ringbone in 1 Japanese sports horse, cellulitis in 1 thoroughbred, melanoma in 1 Lipizzaner) fell outside the group of points for other (non-diseased) horses. A similar separation was seen (using data from other authors) for a horse with Rhodococcus equi, a horse following castration surgery, and a mare following delivery. These results, comparing horses, other animals, and humans, are interesting from the standpoint of comparative medicine, and they contribute to the sparse literature available on d-ROM and BAP levels in animals. Because the level of d-ROM and BAP levels were changed depending on the situation of health, those indexes are promising as indices of health in horses.