New research has found that a horse’s age can significantly influence markers of oxidative stress, highlighting the importance of taking age into account when interpreting laboratory results.
Oxidative stress occurs when there is an imbalance between oxidants and the body’s antioxidant defences. It can lead to cellular damage and has been linked to ageing and a range of diseases. In horses, oxidative stress has previously been studied in relation to exercise, transport and conditions including Pituitary Pars Intermedia Dysfunction (PPID), but relatively little research has looked specifically at how age affects these markers in otherwise healthy horses.
For the new study, researchers assessed 152 clinically healthy horses, including 50 young horses aged between three and 48 months, 76 adults aged between eight and 14 years, and 26 older horses aged between 20 and 30 years.
Blood samples were used to assess a range of laboratory parameters alongside several measures of antioxidant and oxidant capacity.
The researchers found clear age-related differences. Young horses had higher levels of several blood cell types and also showed higher levels of uric acid and one measure of total antioxidant capacity, known as TAC-CUPRAC, compared with older horses.
In contrast, the older horses had lower TAC-CUPRAC and uric acid levels, suggesting that some aspects of antioxidant capacity decrease as horses age. Other laboratory measurements also differed between the young, adult and older groups.
Importantly, all the horses included in the research were considered clinically healthy. This suggests that differences in oxidative stress biomarkers can occur as part of ageing rather than necessarily indicating disease.
The findings could therefore be important for both veterinary research and the interpretation of laboratory results in individual horses. The researchers say age should be considered when evaluating oxidative stress biomarkers and recommend looking at multiple markers to provide a more complete picture of a horse’s oxidative status.
The study, “Oxidative stress markers in different age ranges of healthy horses”, has been published in Research in Veterinary Science.
