The published data regarding oxidative stress in horses is generally concerned with
blood and muscle samples. The aim of this thesis was to use non-invasive markers as a
novel approach to investigate cellular stress in performance and senior horses. In
addition, urine was analysed using IH NMR spectroscopy and renal insult during ageing
and exercise was investigated using urinary N-acetyl-beta-D-glucosaminidase (NAG)
activity.
The results demonstrated that urinary thiobarbituric acid reactive substances (TBARS)
in horses could be measured using a method adapted from Vagi (1976) and were
significantly decreased following supplementation with antioxidants in the form of
dandelion and milk thistle (p<O.05). Urinary TBARS were seen to decrease in horses
supplemented with vitamin E at a level of 4mglkg bodyweight, but subsequently were
unaffected in horses performing a sub-maximal exercise test on a treadmill when
supplemented with vitamin E at a level of 3 mg/kg bodyweight.
Urinary TBARS were seen to increase with age (P<O.05), consistent with increased
lipid peroxidation in senior horses. Analysis using 1 H NMR spectroscopy revealed
higher levels of aromatic amino acids in the urine of senior horses (p<O.05) and
proteinuria quantification using the biuret assay demonstrated increased total
proteinuria in the urine of senior horses compared to young horses (p<O.05). This
indicated that subtle changes in renal, hepatic and endocrine functions may be evident
in senior horses.
TBARS in equine sweat could be measured using a method adapted from Vagi (1976)
and were significantly decreased in horses performing a sub-maximal exercise test on a
treadmill, following vitamin E supplementation (p<O.05). In addition, free radical
scavenging activity of equine saliva could be measured using a method adapted from
Atsumi et al (1999). Urinary NAG activity proved to be difficult to measure in the
horse and may require further investigation to establish its potential use as a marker of
renal insult in horses
