OXIDATIVE STRESS AND PERFORMANCE IN HORSES – PERSPECTIVES FOR CAMELS

Abstract

Intense exercice causes alterations in innate immune system functions and produces a systemic inflammatory reaction characterized by a neutrophil activation leading to an oxidative stress. Reactive oxygen species are mainly generated by activated neutrophils or by mitochondrial dysfunction. Recently, the links between inflammation and mitochondria were clearly demonstrated. Myeloperoxidase, a potent oxidative enzyme, released by activated neutrophils enters in the muscle cells and inhibits the mitochondrial electron transfer chain especially the complex 1. Strenuous exercises undertaken by horses (or camels) during endurance races induce a marked increase of myeloperoxidase and elastase plasma concentration. These enzymes could be responsible for tissue lesions observed in sport horses such as myopathy, tendinitis, fracture or degenerative joint disease. However, large differences exist between the horses for the similar level of exercise. Inflammatory airway disease is an important cause of poor performance in young Thoroughbred racehorses. Neutrophil percentage, myeloperoxidase concentration, haemosiderophage percentage and total bacterial numbers were significantly elevated in broncho alveaolar fluid in horses with exercise intolerance. As camels can be affected by exercise induced pulmonary hemorrhage or other respiratory diseases, we hypothesized that systemic and/or local inflammation leading to oxidative stress and mitochondrial dysfunction occur in this species.