Systemic concentrations of antioxidants and biomarkers of macromolecular oxidative damage in horses with grass sickness.

The research investigates the potential role of oxidative damage and antioxidant levels in a horse disease called Equine Grass Sickness (EGS). All ten horses with EGS studied had altered antioxidant levels, suggesting a possible link, but there was no observed systemic macromolecular oxidative damage.

Study Overview

• This study aimed to understand the potential involvement of oxidative damage and antioxidant status in Equine Grass Sickness (EGS). EGS is a disease in horses, the cause of which is currently not known. Particular attention was given to whether free radical-mediated neuronal damage, a type of cellular damage caused by unstable atoms, might be involved in the disease.

Methods

• The researchers analysed systemic levels of certain biomarkers in 10 horses diagnosed with acute EGS. These biomarkers can indicate the presence of disease in an organism.
• The values from the EGS horses were then compared to two control groups. The first control group consisted of 10 healthy horses that were co-grazing with the EGS horses at the onset of the disease. The second control group consisted of 10 healthy mares grazing in areas where EGS has not been reported.

Results

• The horses with EGS showed changes in the level of several antioxidants, suggesting the presence of oxidative stress, a condition that can lead to cell damage. These alterations could also be due to the acute phase response (a rapid inflammatory response to tissue injury or infection) or secondary metabolic complications related to EGS.
• The EGS horses had increased plasma levels of a molecule called dihydroxyphenylalanine (DOPA). However, the researchers believed that this was likely due to a disturbance in catecholamine metabolism, a chemical pathway involving hormones like adrenaline, rather than increased DOPA production through free radical-mediated oxidation of an amino acid called tyrosine.
• Contrary to what might be expected if oxidative stress was a major factor in EGS, there was no observed evidence of systemic macromolecular oxidative damage, a type of damage that can occur to large molecules in the body (such as proteins, DNA, and fats) due to oxidative stress.

Conclusions

• The researchers concluded more work is needed to determine whether macromolecular oxidative damage, particularly at the neuronal level, contributes to the occurrence or progression of EGS.