Antioxidant and inflammatory responses of healthy horses and horses affected by recurrent airway obstruction to inhaled ozone.
BACKGROUND
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.


OBJECTIVE
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.


CONCLUSIONS
Horses with high susceptibility to oxidative stress may benefit from antioxidant supplementation.
Deaton
C M
CM
Centre for Equine Studies, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, UK.
Marlin
D J
DJ
Smith
N C
NC
Roberts
C A
CA
Harris
P A
PA
Schroter
R C
RC
Kelly
F J
FJ
D000818:Animals; D000975:Antioxidants / Q000032:analysis*; D001205:Ascorbic Acid / Q000032:analysis; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D016022:Case-Control Studies; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006734:Horse Diseases / Q000139:chemically induced / Q000378:metabolism*; D006736:Horses / Q000378:metabolism*; D008173:Lung Diseases, Obstructive / Q000378:metabolism / Q000503:physiopathology / Q000662:veterinary*; D008297:Male; D010083:Oxidants, Photochemical / Q000009:adverse effects*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D010126:Ozone / Q000009:adverse effects*; D012008:Recurrence
D000975:Antioxidants; D010083:Oxidants, Photochemical; D010126:Ozone; D005978:Glutathione; D001205:Ascorbic Acid