Antioxidative status in the plasma of healthy dogs in dependence of age

Introduction Some theories of ageing postulated the involvement of free radicals in the ageing process which is accompanied by a deficiency of antioxidants (AO). The aim of this study was to investigate whether healthy dogs exhibit an age-dependent decrease of AO in blood plasma. Methods 95 pedigreed dogs (45 Beagle and 15 German shepherd dogs) and 9 mongrel dogs, 0.5 to 13.8 years old, were studied. Anamnesis, clinical examination, blood biochemistry and haematology ensured that all dogs (57 males, 47 females) were healthy. Dogs were fed balanced diets not supplemented with additional amounts of vitamins. The status of lipid- and water-soluble AO in plasma of fasted overnight dogs was measured by means of Luminol-induced photochemiluminescence. Results Neither water-soluble AO (35.9 +/- 9.8 vs. 35.5 +/- 10.5 mu mol/l Trolox-equivalents) nor lipid-soluble AO (61.4 +/- 27.0 vs. 53.0 +/- 19.3 mu mol/l alpha-tocopherol-equivalents) showed significant differences in males and females. Likewise no correlation was found between the capacity of water-soluble AO and age or body mass independent of sex. Whereas a slight positive dependency of lipid-soluble AO on age (r = 0.262, p = 0.049) and body mass (r = 0.335, p = 0.011) was observed in males. In the plasma of German shepherd dogs higher capacities of water-soluble AO were detected in comparison to Beagles (p = 0.01, n = 15) whereas no breed differences were found in the levels of lipid-soluble AO. Conclusion On the basis of present data an additional supplementation of AO to healthy ageing dogs fed balanced diets can not be recommended.