Antioxidant and inflammatory responses of healthy horses and horses
affected by recurrent airway obstruction to inhaled ozone.
Centre for Equine Studies, Animal Health Trust,
Lanwades Park, Kentford, Newmarket, Suffolk, UK.
REASONS FOR PERFORMING STUDY: Inhaled ozone can induce
oxidative injury and airway inflammation. Horses affected by recurrent
airway obstruction (RAO) have a decreased pulmonary antioxidant
capacity, which may render them more susceptible to oxidative challenge.
It is currently unknown whether RAO-affected horses are more susceptible
to oxidative stress than those unaffected by RAO. OBJECTIVES: To
determine whether ozone exposure induces greater oxidative stress and
airway inflammation in RAO-affected horses in remission than in healthy
horses. METHODS: Seven healthy control horses and 7 RAO-affected horses
were exposed to 0.8 ppm ozone for 2 h at rest. RESULTS: At baseline,
bronchoalveolar lavage fluid (BALF) ascorbic acid concentrations were
lower in RAO-affected horses than healthy controls. Ozone appeared to
preferentially oxidise glutathione rather than ascorbic acid 6 h after
exposure. Individual healthy and RAO-affected horses demonstrated
oxidation of BALF glutathione after ozone exposure. Overall,
RAO-affected horses did not demonstrate increased oxidative stress
following ozone exposure, compared with healthy horses. Ozone did not
induce significant airway inflammation in either group. CONCLUSIONS:
RAO-affected horses in remission are not more sensitive to ozone despite
a decreased pulmonary antioxidant capacity. Sensitivity to ozone appears
to be independent of initial pulmonary antioxidant status. POTENTIAL
RELEVANCE: Horses with high susceptibility to oxidative stress may
benefit from antioxidant supplementation.
PMID: 15892234 [PubMed - indexed for MEDLINE]