Oxidative stress markers in different age ranges of healthy horses.

Overview

• This study investigated how age affects oxidative stress markers and routine laboratory parameters in clinically healthy horses across different age groups.
• Researchers measured oxidative stress biomarkers alongside blood and biochemical profiles in young, adult, and elderly horses to understand age-related changes.

Background

• Oxidative stress occurs when there is an imbalance between oxidants (molecules that can cause cellular damage) and antioxidants (molecules that neutralize oxidants), leading to cellular dysfunction.
• This imbalance is linked to aging and various diseases.
• Despite its importance, few studies have examined how age influences oxidative stress and laboratory parameters specifically in healthy horses.

Study Objectives

• To evaluate the influence of age on oxidative stress markers and standard laboratory blood tests within a population of clinically healthy horses.
• To identify how these parameters vary between young, adult, and elderly horse groups.

Methods

• A total of 152 clinically healthy horses were enrolled, including:
  • Young horses: 3 to 48 months old (n=50)
  • Adult horses: 96 to 168 months old (n=76)
  • Elderly horses: 240 to 360 months old (n=26)
• Samples were analyzed for:
  • Complete blood count (CBC) – including red/white blood cells, lymphocytes, monocytes, platelets, and related indices like MCV and RDW.
  • Biochemical profile focusing on enzymes and metabolites such as AST and creatinine.
  • Oxidative stress status through measurement of:
    • Total Antioxidant Capacity (TAC), determined by multiple assays:
      • TAC-ABTS (inhibition of ABTS cation reduction alone)
      • TAC-ABTS+HRP (in presence of peroxidase)
      • TAC-FRAP (Ferric reducing antioxidant power)
      • TAC-CUPRAC (Cupric reducing antioxidant capacity)
    • Total Oxidant Capacity (TOC)
    • Antioxidants like uric acid and albumin
• Statistical analysis:
  • Used ANOVA or Kruskal-Wallis test for group comparisons.
  • Significance was set at P < 0.05.

Key Findings

• Young horses (3-48 months):
  • Had higher counts of red blood cells (RBC), white blood cells (WBC), lymphocytes, monocytes, and platelets than adult and elderly horses.
  • Showed higher uric acid concentrations and greater TAC-CUPRAC values compared to elderly horses, indicating stronger antioxidant capability in this assay.
  • Exhibited lower mean corpuscular volume (MCV) and lower TAC-ABTS+HRP values than the other age groups, suggesting some age-dependent variation in antioxidant capacity depending on the method used.
• Adult horses (96-168 months):
  • Showed lower AST (aspartate aminotransferase) and creatinine values compared to young horses, indicating potentially better liver and kidney markers.
  • Had higher red blood cell distribution width (RDW) than young horses, reflecting variation in red blood cell size which may relate to age or physiological status.
• Elderly horses (240-360 months):
  • Generally exhibited lower antioxidant markers (such as uric acid and TAC-CUPRAC) compared to young horses, indicating reduced antioxidant defense with aging.
  • Had oxidative parameters that varied significantly from the other age groups, highlighting age-related oxidative stress changes.

Conclusions and Implications

• There are clear, measurable changes in both standard blood parameters and oxidative stress markers across different age groups in healthy horses.
• Young horses tend to have higher blood cell counts and greater antioxidant capacity in some assays, while elderly horses show signs of diminished antioxidant defenses.
• Adult horses display distinct biochemical profiles different from young and aged groups, implying physiological changes with maturity.
• Age must be taken into account when interpreting oxidative stress and laboratory test results in horses, as normal reference ranges and biomarker levels shift with age.
• Evaluating multiple oxidative stress biomarkers rather than relying on a single measurement provides a more comprehensive understanding of redox status in horses and likely in other species.
• This research contributes valuable baseline data for veterinary clinical assessments and furthers our understanding of aging and oxidative biology in equine health.