Biological and Biochemical Effects of Light Therapy for Horses

This clinical trial investigates the biological and biochemical effects of solarium light therapy in horses, focusing on its therapeutic potential through combined infrared and visible red light wavelengths. Light therapy for horses delivers photobiomodulation to enhance cellular function, reduce inflammation, and improve circulation. Red light therapy stimulates mitochondrial activity, promoting tissue repair and antioxidant production, which are critical for athletic and aging horses. The study examines hematological parameters, oxidative stress markers, and biochemical responses to determine age-related therapeutic efficacy. As natural light diminishes in winter, artificial light therapy may offer vital physiological support, making this research valuable for optimizing equine health management strategies.

This study investigated the effects of light therapy on blood parameters and antioxidant capacity in ten geldings, divided into young (5–7 years) and older (14–19 years) groups at the University of Warmia and Mazury. Conducted from late November to December 2021 at an Equestrian Centre, the horses received ten sessions of light therapy using infrared and UV lamps. Blood samples were collected before therapy, after five sessions, and after ten sessions to evaluate various hematological indices and antioxidative enzyme activities. Results indicated age-related changes in blood parameters and varying responses to light therapy, particularly in antioxidant levels and enzyme activity, with younger horses showing enhanced resilience compared to older ones.

Orzołek A, Rafalska KT, Domosławska-Wyderska A, Rafalska AM, Dziekońska A, Jastrzębska E, Dobbek D. The effect of solarium light therapy on selected biological and biochemical parameters of peripheral blood in young and old horses. PLoS One. 2024 May 24;19(5):e0304290. doi: 10.1371/journal.pone.0304290. PMID: 38787841; PMCID: PMC11125486.

https://doi.org/10.1371/journal.pone.0304290 

The study assessed the influence of light therapy on blood parameters and antioxidant capacity in ten geldings divided into two age groups: young (5–7 years) and older (14–19 years). Conducted in winter at the Equestrian Centre of the University of Warmia and Mazury, the horses underwent ten sessions of 15-minute light therapy every other day. Blood samples were collected at three time points: before therapy, after five sessions, and after ten sessions. Various hematological tests, including white blood cell and red blood cell analyses, were performed, alongside assessments of antioxidant enzyme activities such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR).

The findings indicated that as horses age, there are significant declines in red blood cell (RBC) counts, white blood cell (WBC) counts, and platelet (PLT) values, highlighting reduced bone marrow response. The study noted a notable decrease in lymphocyte counts and increased neutrophil counts in older horses, corroborating established observations. The analysis of antioxidant activity showed that while SOD activity did not correlate with age, GPx activity was notably higher in older horses. In contrast, younger horses exhibited elevated GR activity.

Light therapy for horses enhanced membrane fluidity in erythrocytes, resulting in stable RBC counts and hemoglobin levels despite earlier studies showing hemoglobin degradation in other species. The treatment changed other parameters, such as increased mean corpuscular volume (MCV) and red cell distribution width (RDW). Furthermore, vitamin C levels in both plasma and erythrocytes decreased during treatment, potentially due to its use as an antioxidant. Light therapy demonstrated potential for improving blood indices and antioxidant enzyme activity in horses, with increased efficacy observed in the younger group.

Results of ANOVA confirmed significant effects of age on various blood parameters:

• Lymphocyte Counts (LYMPH): Significantly higher in younger horses.
• Neutrophil Counts (NEUT): Higher in older horses.
• Hemoglobin Content: Higher in older horses.
• Mean Corpuscular Volume (MCV): Higher in older horses (p ≤ 0.05).
• Mean Corpuscular Hemoglobin (MCH): Higher in older horses (p ≤ 0.05).
• Mean Content of Hemoglobin in Reticulocytes (CHr): Higher in older horses (p ≤ 0.05).
• Mean Platelet Volume (MPV): Higher in older horses (p ≤ 0.05).

• Glutathione Peroxidase (GPx) Activity: Significantly higher in older horses.
• Glutathione Reductase (GR) Activity: Similar in both age groups, but in erythrocytes, GR activity was more than twice as high in younger horses (p ≤ 0.05).
• Glutathione (GSH) Content in Blood Plasma: Significantly higher in younger horses.
• GSH Level in Erythrocytes: Comparable between age groups.
• Vitamin C Content in Blood Plasma: Higher in younger horses (p ≤ 0.05).
• Malondialdehyde (MDA) Level: Lower in older animals (p ≤ 0.05).

Light therapy had significant effects on the following blood parameters:

• Morphological Indices: The therapy affected:
  • Mean Corpuscular Volume (MCV)
  • Mean Corpuscular Hemoglobin Concentration (MCHC)
  • Red Cell Distribution Width (RDW)
  • Hemoglobin Distribution Width (HDW)
  • Mean Corpuscular Volume in Reticulocytes (MCVr)
  • Mean Content of Hemoglobin in Reticulocytes (CHr)
  • Mean Platelet Volume (MPV) 

• Catalase (CAT) Activity: Decreased in blood plasma of younger animals post-therapy.
• Glutathione Peroxidase (GPx): Increased in the blood plasma of younger animals.
• Glutathione Reductase (GR): Increased in younger animals.
• Total Antioxidant Status (TAS): Gradually rose during light therapy application (p ≤ 0.05).
• Reticulocyte Counts: Dropped significantly in older horses after five sessions.
• Erythrocyte Parameters: Positive effects included increased values for MCV, HDW, MCVr, CHr, and MPV.

• Vitamin C Levels in Plasma: Influenced by light therapy, with significant differences noted between age groups.
• D3 Levels: No statistically significant differences were observed between age groups.

The data indicated that while both age and light therapy did not significantly affect the morphological parameters of peripheral blood, their influence was notable on:

• Glutathione Reductase (GR) Activity: Different effects observed based on age.
• Total Antioxidant Status (TAS): Strongly influenced by both factors.
• Antioxidant Enzymes: GPx and GR activities in erythrocytes showed variability depending on the age group, suggesting that younger horses may respond more favorably to light therapy in enhancing antioxidant capacity.

Overall, the integration of age and light therapy provided insights into optimizing health and antioxidant support in equine management.

This study concluded that applying light therapy through a solarium unit positively affected both blood parameters and antioxidant capacity in recreational horses during winter. Key findings indicated an increase in hematological indices such as mean corpuscular volume (MCV), hemoglobin distribution width (HDW), reticulocyte indices, and mean platelet volume (MPV). Additionally, there was a decrease in basophil counts, accompanied by changes in mean corpuscular hemoglobin concentration (MCHC) and red cell distribution width (RDW) across both age groups. Young horses exhibited a notable increase in white blood cells and monocyte counts, contrasting with the older group, which showed a decline in reticulocyte counts.

Vitamin C and glutathione (GSH) were identified as crucial antioxidants, while the activities of GPx and GR varied according to GSH demands. The study emphasized the importance of maintaining GSH levels and minimizing oxidative stress for erythrocyte health. Importantly, light therapy proved to be more beneficial for younger horses, suggesting their immune systems are more responsive to such treatments. These findings underscore light therapy's potential as a method to support the health and performance of horses, particularly in managing oxidative stress during winter months.