Physiological determinants of plasma biochemical parameters in horses: a structured review.

Overview

• This article reviews how various physiological factors influence blood biochemical parameters in horses under normal, healthy conditions.
• It highlights the need to consider these factors when interpreting lab results to improve diagnostic accuracy and treatment in equine practice.

Introduction to Equine Biochemical Profiles

• Biochemical profiles measure substances in the blood such as enzymes, metabolites, electrolytes, and hormones.
• These profiles provide critical information about a horse’s health, disease status, and physiological adaptations.
• They are widely used in veterinary diagnostics to detect illness, monitor progression, and guide treatments.
• However, interpreting these values can be complex due to natural variations influenced by physiological factors unrelated to disease.

Physiological Factors Affecting Biochemical Parameters

• Age:
  • Biochemical values can vary with developmental stage and aging processes.
  • Values typical for foals may differ appreciably from those in adults or senior horses.
• Sex:
  • Male and female horses may show differences in hormone levels and related biochemical markers.
  • Reproductive status (e.g., pregnancy) also affects some analytes.
• Breed:
  • Different breeds may have baseline biochemical differences reflective of genetic and physiological variation.
• Physical Activity Level:
  • Exercise influences muscle enzyme activity, energy metabolites, and stress hormones.
  • Values may fluctuate before, during, and after physical exertion.
• Nutritional Condition:
  • Diet and nutritional status can alter protein, metabolite, and electrolyte levels.
  • Starvation, obesity, or specific nutrient imbalances have distinct biochemical signatures.
• Reproductive Status:
  • Pregnancy and lactation can drastically modify hormonal and metabolic profiles.

Implications for Clinical Practice

• Because physiological factors can shift biochemical values, static reference ranges may be insufficient.
• Establishing context-specific reference intervals considering age, sex, breed, activity, and reproductive status improves diagnostic accuracy.
• Veterinarians should adopt an individualized, integrative approach when assessing biochemical results.
• This approach minimizes misinterpretation of normal physiological variations as pathological changes.
• Ultimately, this leads to better clinical decision-making and targeted therapeutic interventions.

Conclusion

• The review underscores the complexity underlying plasma biochemical parameters in horses.
• It calls for increased awareness and incorporation of physiological determinants to refine equine diagnostics.
• Such measures enhance the reliability of lab tests as tools for monitoring equine health and disease.