Association Between Vaquejada Practice and Biomarkers of Oxidative Stress, Inflammation, and Muscle Damage in Quarter Horses.

Overview

• This study investigates how participation in Vaquejada, a traditional Brazilian equestrian sport, affects blood markers related to oxidative stress, inflammation, and muscle damage in Quarter Horses.
• It compares conditioned Vaquejada athletes to sedentary control horses to identify hematological and biochemical changes associated with this high-performance training.

Introduction to Vaquejada and Study Aim

• Vaquejada (VQ) is a popular Brazilian sport requiring high physical exertion from Quarter Horses (QH), leading to potential physiological stress.
• The study aimed to explore how VQ training affects blood biomarkers related to oxidative stress, inflammation, and muscle damage, which are critical indicators of animal health and performance.
• By understanding these changes, the study seeks to improve management strategies to protect horse health during and after intense training or competition.

Study Design and Methodology

• Sample: 70 healthy Quarter Horses were studied, divided into two groups:
  • 60 VQ-conditioned athlete horses (Athlete Group, AG).
  • 10 sedentary, non-exercised breeding horses (Control Group, CG).
• Blood samples were collected at rest to analyze baseline biomarker levels rather than acute exercise-related changes.
• Biomarkers analyzed included hematological parameters (e.g., red blood cells, lymphocytes), biochemical markers (e.g., catalase, malondialdehyde), and inflammatory markers (e.g., myeloperoxidase, neutrophils, platelets).
• Data analysis used Linear Mixed Models to compare groups and identify statistically significant differences.

Key Findings: Hematological Changes

• VQ-conditioned horses showed decreased counts of:
  • Erythrocytes (red blood cells), indicating potential impacts on oxygen transport or blood homeostasis.
  • Lymphocytes, which are white blood cells critical for immune defense, suggesting possible immunosuppression or altered immune function.
• In contrast, band neutrophils (a type of immature white blood cell) were increased in the athlete group, possibly reflecting ongoing immune activation or stress response.
• Platelet counts were also elevated, which may relate to stress or inflammatory signaling although inflammation was less prominent overall.

Oxidative Stress Biomarkers

• There were significant reductions in antioxidant enzymes such as catalase and myeloperoxidase in the VQ athlete horses compared to controls, indicating a reduced capacity to neutralize reactive oxygen species.
• Malondialdehyde (MDA), a marker of lipid peroxidation and oxidative damage to cell membranes, was markedly elevated in the athlete group, revealing pronounced oxidative stress induced by VQ practice.
• These findings suggest that the physical demands of VQ induce strong oxidative stress, potentially overwhelming the horses’ antioxidant defense mechanisms.

Inflammation and Muscle Damage

• The study observed an increase in certain immune cell types (band neutrophils, platelets) but overall concluded that horses experienced oxidative stress rather than classical inflammatory damage.
• No strong evidence of muscle damage markers was emphasized, implying that oxidative damage may be a primary concern rather than direct muscle injury.
• This distinction is important as oxidative stress and inflammation, although often related, have different management implications.

Implications and Recommendations

• The altered biomarker profile indicates that Vaquejada exerts significant physiological stress, impacting immune function and promoting oxidative damage.
• Given the oxidative stress persists at least 96 hours post-exercise, careful dietary strategies focused on antioxidant support may aid recovery and reduce harm.
• Regular monitoring of oxidative and inflammatory biomarkers in VQ horses is recommended to optimize training loads and improve overall health and performance.
• These findings emphasize the importance of integrating biomarker analysis into equine sports medicine to safeguard athlete horses against longer-term deleterious effects.