Oxidative stress in endurance horses

Metabolički i oksidacijski stres u konja daljinskog jahanja

Nika Brkljača Bottegaro, DVM, PhD, Assistant Professor
Clinic for Surgery, Orthopaedics and Ophthalmology, Faculty of Veterinary Medicine, University of Zagreb, Croatia; e-mail: nikabb@vef.hr

Izlaganje sa 3. međunarodnog veterinarskog specijalističkog simpozija

Hitni postupci u liječenju malih životinja

Izvor: Knjiga sažetaka 3. međunarodnog veterinarskog specijalističkog simpozija “Hitna i intenzivna skrb u veterinarskoj medicini”

Endurance riding is the most demanding equine discipline since horses compete over distances of 80–160 km in a day. In the last decade, the popularity of this discipline has raised significantly not just among riders but also among researchers. An endurance ride is divided into several phases of 20 to 40 km each followed by a mandatory resting period. Before the ride, as well as after each phase, horses have to pass a veterinary examination. Veterinarians can eliminate the horse at any stage of the ride if their metabolic status or orthopaedic condition are found inadequate to enable them to continue the ride. Orthopaedic injuries occur frequently during races, in particular in exhausted horses. Despite rigorous veterinary controls every year, there are about ten cases of equine fatalities associated with endurance rides, therefore a lot of efforts is put in research in order to better understand the influence of the race on the horse body.

Endurance riding is characterized as a prolonged submaximal aerobic exercise with an increased consumption of oxygen providing energy for homeostasis. Most of the oxygen is reduced and forms carbon dioxide, however, a 1 to 2% of the oxygen forms reactive oxygen species (ROS). Antioxidants prevent oxidant damage by scavenging of ROS, increasing the conversion of less reactive ROS, and facilitating repair of the caused damage. Oxidative stress reflects an imbalance between the systemic manifestation of ROS and a biological system’s anti-oxidative response and can be assessed by measuring different biomarkers. When pro oxidants overcome antioxidative defence, oxidative stress negatively affects health and performance of horses. Oxidative stress causes immediate and/or cumulative deleterious effects contributing to several equine diseases like osteochondrosis disecans, exertional rhabdomyolysis, exercise-induced pulmonary haemorrhage, and degenerative motor neuron disease.

Endurance race induces increased values of selected oxidative stress biomarkers in horses indicating an enhanced oxidative damage. Concurrently, endurance exercise causes an increase in antioxidants as a response to an increased amount of ROS.
Interestingly, an increase in both prooxidants and antioxidants is evident also during shorter, qualification races where younger and less experienced horses are competing.

Since the antioxidant response is more pronounced in relation to endurance races, antioxidant supplementation in sport horses could be beneficial. However, oxidative stress biomarkers are still not completely understood and there are possible physiologic variations that can be influenced by unknown determinates. Besides, in order to better understand the influence of oxidative stress on injuries in endurance horses further studies are needed. Considering the growing interest in this equine discipline it is even
more important to ensure the best possible understanding of the race influence on horse’s body and consequently minimize the negative effects.

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Metabolički i oksidacijski stres u konja daljinskog jahanja

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